Hydro(trispyrazolyl)borato-Ruthenium(II) Diphosphinoamino Complex-Catalyzed Addition of b-Diketones...

DOI: 10.1002/adsc.201000567

Hydro(trispyrazolyl)borato-Ruthenium(II) DiphosphinoaminoComplex-Catalyzed Addition of b-Diketones to 1-Alkynes andAnti-Markovnikov Addition of Secondary Amines to Aromatic1-Alkynes

Hung Wai Cheung,a Chau Ming So,a Kwok Hung Pun,a Zhongyuan Zhou,a

and Chak Po Laua,*a Department of Applied Biology & Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon,

Hong Kong, People�s Republic of ChinaFax: (+852)-2364-9932; e-mail: [email protected]

Received: July 19, 2010; Revised: December 19, 2010; Published online: February 16, 2011

Abstract: The hydro(trispyrazolyl)borato-rutheniu-m(II) diphosphinoamino complex TpRu[4-CF3C6H4NACHTUNGTRENNUNG(PPh2)2] ACHTUNGTRENNUNG(OTf) (I) [Tp=hydro(trispyrazo-lyl)borate] catalyzes the Markovnikov addition of b-diketones to unactivated 1-alkynes in good to excel-lent yields. The reaction proceeds under solvent-freeand additive-free conditions and the catalyst loading

can be reduced down to 0.4 mol%. Complex I(1 mol%) also catalyzes the addition of secondaryamines to aromatic terminal alkynes, unusual anti-Markovnikov products are exclusively formed.

Keywords: addition reaction; 1-alkynes; b-diketones;ruthenium; secondary amines

Introduction

The addition of 1,3-dicarbonyl compounds to unacti-vated alkynes under neutral conditions without priorenolate formation represents an attractive and atomeconomical method for the formation of carbon-carbon bonds. The intramolecular addition reactionwas exemplified by the gold(I)-catalyzed Conia-enereaction of b-keto esters with alkynes reported byToste and co-workers; the reaction proceeds underneutral conditions at room temperature.[1] Yang andco-workers reported the Ni ACHTUNGTRENNUNG(acac)2/Yb ACHTUNGTRENNUNG(OTf)3-cata-lyzed intramolecular addition of acetylenic 1,3-dicar-bonyl compounds.[2] On the other hand, an intermo-lecular version of the addition reaction catalyzed byindium triflate was reported by Nakamura and Naka-mura.[3] The rhenium complex [ReBr(CO)3ACHTUNGTRENNUNG(THF)]2

was found to be an active catalyst for both inter- andintramolecular addition reactions of 1,3-dicarbonylcompounds with terminal acetylenes under mild con-ditions.[4] These reported catalytic systems are, in gen-eral, only efficient for the intramolecular and/or inter-molecular addition of the b-keto esters to terminal al-kynes. In contrast, the intermolecular addition of the1,3-diketones to terminal alkynes requires harsh reac-tion conditions such as high catalyst loading, hightemperature, long reaction time, and large excess ofalkynes; moreover, in some cases, addition of n-BuLi

is required to suppress the by-product formation so asto obtain the desired products in good yields.[3]

Catalytic intra- and intermolecular additions of N�H bond to alkynes providing cyclic enamines/iminesand enamines/imines, respectively, are important or-ganic transformations as the products are useful inter-mediates for further synthetic elaboration; these pro-cesses are highly atom-economical as no waste is gen-erated.[5] The hydroamination of terminal alkynes pro-vides additional challenges in terms of regioselectivity.A variety of metals including early, late transitionmetals, lanthanides, and actinides are capable of cata-lyzing the intermolecular addition of N�H bonds toterminal alkynes yielding Markovnikov products ormixtures of Markovnikov and anti-Markovnikovproducts.[6] On the other hand, highly regioselectivecatalytic systems generating anti-Markovnikov prod-ucts are relatively rare. The organouranium complexCp*2UMe2 was the first catalyst for the anti-Markov-nikov hydroamination of terminal alkynes with pri-mary amines.[7] It was then learned that some titano-cene derivatives catalyzed the anti-Markovnikov hy-droamination of terminal alkynes with bulky primaryaliphatic amines.[8] Unlike the titanocene-based cata-lyst systems, the bis ACHTUNGTRENNUNG(amidate)titanium complexes em-ployed by Schafer for terminal alkyne hydroamina-tion demonstrate high regioselectivity in favor of anti-Markovnikov hydroamination of terminal alkynes

Adv. Synth. Catal. 2011, 353, 411 – 425 � 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 411

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with primary alkylamines regardless of the steric bulkin either the amine or the alkyne substrate.[9] TheCsOH-catalyzed hydroamination of phenylacetylenewith substituted anilines and N-heterocycles was theonly known example of anti-Markovnikov addition ofsecondary amines to terminal alkynes until recentlywhen it was reported that TpRhACHTUNGTRENNUNG(C2H4)2/PPh3 catalyz-es the anti-Markovnikov hydroamination of terminalalkynes with secondary amines as well as primaryones.[10–11] We report here that a hydrotris(pyrazolyl)-borate ruthenium complex supported by a diphosphi-noamine ligand is an excellent catalyst for the addi-tion of b-diketones to 1-alkynes and is also effective

for the unusual anti-Markovnikov addition of secon-dary amines to aromatic terminal alkynes.

Results and Discussion

For the addition reactions of 1,3-dicarbonyl com-pounds to 1-alkynes, a metal center with appropriateelectrophilicity is generally required for the coordina-tion and activation of the alkynes. We have beenworking with ruthenium complexes supported by hy-drotris(pyrazolyl)borate (Tp) ligands for more than adecade; we therefore first studied the catalytic activityof the TpRu complexes VI–VIII (Figure 1) for the ad-

Figure 1.

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dition of acetylacetone (1a) to phenylacetylene (2a).These complexes, however, were found to be of verylow activity or inactive for the reaction (entries 6–8,Table 1). We then turned to the Tpm-supported Ruspecies (IX) [Tpm = tris(pyrazolyl)methane] which isdicationic and highly electrophilic, but only to findthat it is also inactive (entry 9, Table 1). The TpRucomplexes I–IV (Figure 1) contain the amine-bridgeddiphosphinoamine ligands. These ligands, which offermore opportunities for electronic and steric tuningthan the dppm analogue, have played important rolesin chromium-catalyzed ethylene trimerization and tet-ramerization reactions.[13] It has also been suggestedthat the propensity for back-bonding by the diphos-phinoamine ligand is at least similar to, if not greaterthan, that of the carbonyl group.[14] We thereforeexpect the electrophilicity of complexes I–IV to behigher than that of VI–VIII, but lower than that ofthe TpmRu species IX. We also included complex Vcontaining the N,N-bis(diphenylphosphinomethylene)-ACHTUNGTRENNUNGbutylamine ligand, which has a methylene group sepa-rating the nitrogen and the phosphorus atoms. Com-plexes I–V were prepared by ligand substitution ofTpRu ACHTUNGTRENNUNG(PPh3)2Cl and subsequent chloride removal withAg+OTf� in the absence or presence of acetonitrile

(Scheme 1). Complexes I–V were found to be signifi-cantly more active than VI–IX (entries 1–5, Table 1).The solvent complexes II and IV exhibit lower cata-lytic activity than the corresponding triflate com-plexes I and III, respectively, probably due to the factthat acetonitrile is a more strongly coordinatingligand than the triflate. The complexes containing themore electron-withdrawing 4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2 ligand(I and II) seem to be better catalysts than the onescontaining PNP ligands with a n-butyl substituent onthe phenyl ring (III and IV). Complex V shows muchlower catalytic activity in comparison to the analo-gous triflate complex IV. The screening of catalyticactivity of the complexes for the addition reaction of1a to 2a reveals that complex I is the most active cata-lyst for the reaction and it was therefore chosen asthe catalyst for further study of the reaction depictedin Eq. (1) in Table 2.

TpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2]OTf (I)-CatalyzedAddition of b-Diketones to 1-Alkynes

Table 2 shows the results of the I-catalyzed additionof b-diketones to terminal alkynes. In general, we ob-served complete conversion within 6 h when0.4 mol% of I was used. Acetylacetone is alkenylatedwith phenylacetylenes with excellent yields; substitu-ents on the phenyl ring of the alkynes do not inducepronounced electronic effects (entries 1–5, Table 2).

Aliphatic alkynes 2g–2j (entries 7–10, Table 2) andthe heterocyclic 3-ethynylthiophene 2f (entry 6,Table 2) are also active substrates. Bulky dibenzoyl-methane (1c) (entry 12, Table 2) and the unsymmetri-cal diketones 1b and 1d (entries 11 and 13, Table 2)are also transformed to the corresponding products ingood yields; prolonged heating is, however, requiredfor 1c. It is worth noting that I is a more efficient cat-alyst than those previously reported for the additionof b-diketones to 1-alkynes in terms of catalyst load-ing and turnover frequency. Furthermore, unlikemany known catalytic addition reactions which areplagued by dimer/oligomer side-products, no alkynedimers and/or oligomers were formed as side-productin the I-catalyzed reactions; large excesses of the 1-al-kynes were not required for this catalytic system, only1.2 equivalents of 1-alkyne relative to the b-diketoneswere sufficient to give the desired products in excel-lent yields. Moreover, addition of n-BuLi and a strongbase such as DBU or Et3N is not required in the cata-lytic system. Furthermore, the I-catalyzed addition ofb-diketones to 1-alkynes can be performed under sol-vent-free condition. It should, however, be pointedout that attempted I-catalyzed addition reactions ofb-keto esters and b-keto diesters to phenylacetyleneswere not successful. Moreover, the attempted Conia-ene reaction of 3-(pent-4-ynyl)pentane-2,4-dione (1e)

Table 1. TpRu(II) complexes-catalyzed addition of acetyl-ACHTUNGTRENNUNGacetone with phenylacetylene.[a]

[a] Reaction conditions: catalyst (0.005 mmol), acetylacetone(1.25 mmol), phenylacetylene (1.5 mmol); 120 8C.

[b] Conversion (based on acetylacetone) determined by1H NMR spectroscopy.

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Hydro(trispyrazolyl)borato-Ruthenium(II) Diphosphinoamino Complex-Catalyzed Addition of b-Diketones


gives a poor yield of the intramolecular additionproduct (entry 14, Table 2).

NMR Monitoring of the I-Catalyzed Addition ofAcetylacetone to Phenylacetylene

To gain more information on the possible reactionmechanism of the catalytic reaction, the I-catalyzedaddition of acetylacetone to phenylacetylene wasmonitored by NMR spectroscopy. Several solutionsprepared from the same mother solution containing Iand the substrates were heated in sealed tubes in thesame oil bath at 120 8C. The tubes were removedfrom the oil bath at different times; an aliquot wastaken from each tube and studied by NMR spectros-copy. Figure 1 shows the 31P{1H} NMR spectra of thesamples which had been heated for different periodsof time, the column at the right shows the percentconversions to the product. The 31P{1H} NMR spec-trum (in benzene-d6) of the sample after 5 min ofheating showed a signal at d =75.9 ppm due to the vi-

nylidene complex {TpRu[4-CF3C6H5N ACHTUNGTRENNUNG(PPh2)2] ACHTUNGTRENNUNG(=C=CHPh)}+OTf� (Ia), a very minor signal (d=90.9 ppm)attributable to the alkynyl species TpRu[4-CF3C6H5N-ACHTUNGTRENNUNG(PPh2)2] ACHTUNGTRENNUNG(C�CPh) (Ib) was also observable; the inten-sity of this peak grew with time at the expense of thatof the signal of Ia ; Ib became the dominant speciesafter 30 min; at this time a very minute signal due tothe carbonyl species {TpRu[4-CF3C6H5N-ACHTUNGTRENNUNG(PPh2)2](CO)}+OTf� (Id) was observable at d=80.6 ppm. Compound Id was probably formed via areaction sequence outlined in Scheme 2; the reactionsequence is similar to that proposed by Bianchini etal., who found that reaction of n-PrN(CH2CH2PPh2)2Ru ACHTUNGTRENNUNG(PPh3)Cl2 with excess phenyl-ACHTUNGTRENNUNGacetylene and water led to quantitative formation ofthe carbonyl species n-PrN(CH2CH2PPh2)2Ru(CO)Cl2,with one equivalent of toluene formed as by-prod-uct.[15] The important step for the formation of Id isthe nucleophilic attack of H2O at the a-carbon of thevinylidene moiety of Ia. However, the NMR monitor-ing experiment (Figure 2) shows that Id only startedto appear after most of Ia had disappeared and the

Scheme 1.




Table 2. TpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2] ACHTUNGTRENNUNG(OTf) (I)-catalyzed addition of b-diketones to 1-alkynes.[a]

[a] Reaction conditions: catalyst (0.005 mmol), dicarbonyl compound (1.25 mmol), terminal alkyne (1.5 mmol); 120 8C.[b] Isolated yield (based on b-diketone).[c] Under 10 bar Ar.[d] Catalyst (0.03 mmol), 1e (1 mmol).




signal of the former continues to gain abundanceeven after the signal of the latter had totally vanished.This phenomenon is only explainable in terms of thepresence of a very minute and NMR undetectableamount of Ia in the system throughout the catalyticprocess (vide infra).

The 31P{1H} NMR monitoring showed that the al-kynyl complex Ib was the dominant metal-containing

species throughout the catalytic process and it wasprobably generated via deprotonation of the vinyli-dene complex Ia. Since no base was added to the re-action mixture, we suspect that adventitious water inthe substrates, which were not dried, might be the re-agent that deprotonated the vinylidene species to giveIb and H3O

+OTf�. We therefore treated the acetyl-ACHTUNGTRENNUNGacetone and phenylacetylene with 4 � molecular

Scheme 2.

Figure 2. 31P{1H} NMR study of TpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2] ACHTUNGTRENNUNG(OTf) (I)-catalyzed addition of acetylacetone to phenylacetylene.




sieves and repeated the 31P{1H} NMR montoring ex-periment with these �dried� substrates. The NMRstudy showed that with the �dried� substrates, the dis-appearance and the growing in of Ia and Ib, respec-tively, took place in a much slower pace; the latteronly became the dominant species after nearly 2 h. Itis also noteworthy that only 27% conversion was ob-tained with the �dried� substrates after 3 h, whereaswith �undried� substrates gave 89% conversion. Thedata seem to support the notion that adventitiouswater in the system deprotonates 1a to form 1b andthe conjugated acid H3O

+OTf�.

NMR Monitoring of Addition of Acetylacetone toPhenylacetylene Catalyzed by TpRu[4-CF3C6H4NACHTUNGTRENNUNG(PPh2)2] ACHTUNGTRENNUNG(C�CPh) (Ib)/H3O

+OTf�

The alkynyl complex Ib, which seems to be the restingstate of the I-catalyzed addition of acetylacetone tophenylacetylene, was independently prepared. This in-

dependently prepared Ib was found to be inactive forthe addition reaction; however, upon addition of1 equivalent of H3O

+OTf�, it became active, showinga catalytic activity similar to that of I. It can be seenfrom the NMR monitoring experiment shown inFigure 3 that upon addition of 1 equivalent ofH3O

+OTf� at room temperature, Ib was immediatelyconverted to Ia. However, after heating at 120 8C for30 min, Ib reappeared and it became the dominantspecies throughout the monitoring experiment. Themonitoring experiment was carried out with a proce-dure similar to that for the NMR monitoring experi-ments mentioned in previous sections. To eliminatethe possibility of the reaction being catalyzed by theHOTf or H3O

+OTf, we attempted the addition reac-tion of acetylacetone to phenylacetylene in the ab-sence of complex I but with addition of 1 equivalentof HOTf (relative to the amount of I used in catalyticreactions reported in Table 2); however, no yieldcould be obtained after heating at 120 8C for 24 h.

Figure 3. 31P{1H} NMR study of TpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2]ACHTUNGTRENNUNG(C�CPh) (Ib)-catalyzed addition of acetylacetone to phenylacety-lene.




The same result was obtained using H3O+OTf� in

place of HOTf.When the observations of the NMR monitoring ex-

periments are taken together, it seems that at roomtemperature H3O

+OTf� readily protonates Ib to formIa, probably via tautormerization of the h2-alkynecomplex TpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2](h2-HC�CPh)(Ic), which is the kinetic product of protonation of Ib ;however, at 120 8C, the reversed reaction, that is, de-protonation of Ia by water to generate Ib, dominates.We suggest that in the course of catalysis (at 120 8C),the conjugated acid H3O

+OTf� formed via deprotona-tion of Ia with water, might have reacted with otherspecies present in the catalytic system and form a newacidic species of diminished acidity; its ability to pro-tonate 1b is low so that the amount of Ia regeneratedvia this process is so small that it is not detectablewith 31P{1H} NMR spectroscopy. It was previously re-ported that in FSO3H, H2SO4, or dilute FSO3H-SbF3-SO2 solution, the b-diketone is monoprotonated togive a monocation having the structure A, which wasobserved by 1H NMR spectroscopy [Eq. (2)].[16]

Theoretical calculations for protonated acetylace-tone revealed that the ion containing an intramolecu-lar hydrogen bond (cyclic structure B) is the lowenergy conformation.[16] We suggested that the acidH3O

+OTf� might have been trapped by the b-dike-tone to form an adduct (HDK+), the structure ofwhich we cannot predict.

Proposed Mechanism for the I-Catalyzed Addition ofb-Diketones to 1-Alkynes

The regioselectivity of the addition reaction showsthat the Markonikov product could not be formed viaattack of the b-diketone at the vinylidene moiety ofIa or the alkynyl group of Ib ; on the other hand, reac-tion of b-diketone with the tautomer of Ia, the h2-alkyne complex TpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2](h2-HC�CPh) (Ic) could yield the the Markonikov additionproduct. The h2-alkyne complex Ic has, however,never been observed in the NMR monitoring experi-ments. Scheme 3 shows a proposed mechanism for theaddition reaction (using acetylacetone and phenylace-tylene as model substrates). We are of the opinionthat a combination of Ib and HDK+ might have con-stituted an active system for the addition reaction.HDK+ might, to a very small degree, partially proton-ate Ib to generate a very minute and NMR-undetecta-ble amount of h2-alkyne tautomer Ic ; it is immediate-ly attacked, prior to its tautormierization to the vinyli-

Scheme 3.




dene species Ib, by the b-diketone or its enol formwhich originates from HDK+ and is in close proximity.For ruthenium, it is common knowledge that the h1-vinylidene species is thermodynamically more stablethan the h2-alkyne complex.[17] A recent kinetic studywith indenylruthenium species supports the hypothe-sis that the h2-alkyne tautomer is formed under transi-ent conditions and tautomerizes readily to the h1-vi-nylidene complex.[18]

TpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2]OTf (I)-CatalyzedAddition of Secondary Amines to Aromatic 1-Alkynes

Besides the catalytic addition of b-diketones to termi-nal alkynes, we found that I is also an effective cata-lyst for the hydroamination of terminal alkynes. Sev-eral amines are used to screen the feasibility of the I-catalyzed hydroamination reactions. It was found thatonly secondary amines are active, reactions with pri-mary amine failed. Diethylamine, pyrrolidine, and pi-peridine added to phenylacetylene to give products inmoderate yields. However, the bulky and less nucleo-philic diphenylamine gives no product yield. Substitu-ents on the phenylacteylene do not seem to havemuch effect on the conversions. It is noteworthy thatthe I-catalyzed hydroamination reactions are highlyselective, the anti-Markovnikov products in transforms are formed exclusively; moreover, catalystloadings in our reactions are much lower than thoseused in the other two catalytic reactions previously re-ported.[10,11]

We monitored the hydroamination of alkyne (PhC�CH/Et2NH) with 31P{1H} NMR spectroscopy. Afterheating the reaction mixture for 5 min, it was shownby 31P{1H} NMR spectroscopy that about two thirds ofI was converted to the alkynyl complex Ib, and com-plete conversion to the latter was observed after heat-ing for 3 h. Complex Ib remained the only rutheniumspecies detected throughout the monitoring period(24 h). At this stage, it is difficult to speculate on thepossible mechanism of the I-catalyzed hydroamina-tion reaction; however, the regioselectivity of the re-action seems to suggest that the vinylidene species Iamight be an important though transient intermediatein the reaction since nucleophilic attack of the amineat the a-carbon of the vinylidene moiety would mostlikely lead to the formation of the anti-Markovnikovproduct.

Conclusions

We have found that a TpRu complex supported by adiphosphinoamine ligand is an excellent catalyst forthe addition of b-diketones to 1-alknyes. We believe

that the I-catalyzed addition of b-diketones to 1-al-knyes is a good alternative for the existing catalyticprocesses. Complex I is also capable of catalyzing theunusual anti-Markovnikov addition of secondaryamines to terminal alkynes. It is very interesting tonote that the I-catalyzed addition of b-diketones to 1-alkynes follows the Markovnikov addition pattern,while the regioselectivity of the hydroamination of 1-alkynes is exclusively anti-Markovnikov. More inter-estingly, the two reactions seem to have an identicalcatalyst resting state, that is, a ruthenium alkynyl spe-cies Ib. To account for the regioselectivities of the ad-dition reactions, we proposed that in the addition ofb-diketones to 1-alkynes, the active species is theruthenium h2-alkyne complex; on the other hand, inthe hydroamination reactions, generation of the anti-Markovnikov product is more likely due to nucleo-philic attack of the vinylidene complexes by theamine. Both complexes are transient species in thecourse of the catalytic reactions.

Experimental Section

Materials and Instrumentation

All manipulations were carried out under a nitrogen atmos-phere using standard Schlenk techniques. Solvents werefreshly distilled under nitrogen from sodium-benzophenone(tetrahydrofuran), sodium (diethyl ether, hexane and tolu-ene), calcium hydride (dichloromethane, chloroform andacetonitrile), magnesium-iodine (methanol and ethanol) orP2O5 (C6D6 and CDCl3); they were degassed prior to use.Elemental analyses were performed by M-H-W Laborato-ries, Phoenix, AZ (USA). 1H NMR spectra were obtainedfrom a Bruker DPX-400 spectrometer at 400.13 MHz;chemical shifts (d, ppm) are reported relative to residualpeaks of the deuterated solvents used. 13C{1H} NMR spectrawere recorded with a Bruker DPX-400 spectrometer at100.61 MHz; chemical shifts were internally referenced toCDCl3 (d=77.7 ppm), C6D6 (d=128.1 ppm) or (CD3)2CO(d=206.26, 29.84 ppm). 31P{1H} NMR spectra were recordedon a Bruker DPX-400 spectrometer at 161.70 MHz; chemi-cal shifts were externally referenced to 85% H3PO4 in D2O(d=0.00 ppm). 19F NMR spectra were recorded on a VarianInova AS 500 NMR spectrometer at 470.22 MHz; chemicalshifts were externally referenced to trifluorotoluene in C6D6

(d=�62.5 ppm). All spectra were obtained at ambientprobe temperature unless stated otherwise. High-pressureNMR studies were carried out in commercial 5 mm Wilmadpressure-valved NMR tubes. Infrared spectra were obtainedfrom a Bruker Vector 22 FT-IR spectrophotometer. Massspectrometry was carried out with a Finnigan MAT 95Smass spectrometer with the samples dissolved in dichloro-methane or acetone. HR-MS was carried out with a WatersMicromass Q-Tof-2. The ligands N,N-bis(diphenylphosphi-no)butylamine [n-BuN ACHTUNGTRENNUNG(PPh2)2],[19] N,N-bis(diphenylphosphi-nomethylene)butylamine [n-BuN ACHTUNGTRENNUNG(CH2PPh2)2]

[20] and thecomplexes TpRuACHTUNGTRENNUNG(PPh3)2Cl,[21] [TpRu ACHTUNGTRENNUNG(PMe3)2 ACHTUNGTRENNUNG(CH3CN)]+PF6

�

(IV),[22] [TpRuACHTUNGTRENNUNG(PPh3)2ACHTUNGTRENNUNG(CH3CN)]+BF4� (VII),[23] [TpRu-




ACHTUNGTRENNUNG(dppm) (CH3CN)]+OTf� (VIII)[22] and [TpmRu ACHTUNGTRENNUNG(PPh3)2ACHTUNGTRENNUNG(CH3CN)]2+ (BF4�)2 (XI)[24] were prepared according to lit-

erature methods.

4-(Trifluoromethyl)-N,N-bis(diphenylphosphino)-benzeneamine [4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2]

To a stirred solution of 4-(trifluoromethyl)aniline (0.63 mL,5.0 mmol) in toluene (40 mL), NEt3 (5 mL) was added, fol-lowed by dropwise addition of Ph2PCl (2.0 mL, 11 mmol).After complete addition, the mixture was heated at 80 8Cfor 16 h. At the end of this period, the solution was cooledto room temperature and the insoluble material was filteredout. The solvent of the filtrate was evaporated under re-duced pressure and a white paste was obtained. Pre-cooledhexane (5 mL) was added to the residue, with stirring, toproduce a white solid. The solid was filtered out and driedunder vacuum at room temperature; yield: 1.27 g (48%).1H NMR (400.13 MHz, C6D6, 25 8C): d=7.74–7.70 (m, 8 H),7.28–7.27 (m, 12 H), 7.20–7.17 (m, 4 H); 31P{1H} NMR(161.7 MHz, C6D6, 25 8C): d= 68.62 (s).

TpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2]Cl

The complex TpRu ACHTUNGTRENNUNG(PPh3)2Cl (2.0 g, 2.3 mmol) and theligand 4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2 (1.3 g, 2.5 mmol) were dissolvedin freshly degassed toluene (20 mL); the resulting solutionwas refluxed with stirring for 4 h. At the end of this period,the solution was cooled to room temperature and evaporat-ed to dryness under reduced pressure to yield a pale yellowpaste. Hexane (15 mL) was added to the residue, with stir-ring, to produce a pale yellow solid. The solid was filteredout and washed with diethyl ether (2� 10 mL). It was col-lected and dried under vacuum at room temperature; yield:1.47 g (73%); anal. calcd. (%) for C40H34BClF3N7P2Ru: C54.66, H 3.90, N 11.15; found: C 54.61, H 3.97, N, 11.03; IR(KBr): n(B�H) =2486 cm�1 (br); 1H NMR (400.13 MHz, C6D6,25 8C): d=8.44–8.47 (m, 4 H, PPh2-H), 7.82 (s, 2 H, Tp-H),7.59–7.62 (m, 4 H, PPh2-H), 7.54 (d, 2 H, Tp-H), 7.43 (d, 1 H,Tp-H), 7.28–7.32 (m, 4 H, PPh2-H), 7.30 (d, 2 H, 4-CF3C6H4N-), 7.16 (d, 2 H, 4-CF3C6H4N-), 6.94–6.96 (m, 4 H,PPh2-H), 6.81–6.85 (m, 4 H, PPh2-H), 5.94 (s, 2 H, Tp-H),5.36 (d, 1 H, Tp-H), 5.22 (t, 1 H, Tp-H); 31P{1H} NMR(161.7 MHz, C6D6, 25 8C): d= 88.80 (s); ESI-MS: m/z=879.02, [M]+.

TpRu ACHTUNGTRENNUNG[n-BuN ACHTUNGTRENNUNG(PPh2)2]Cl

A procedure similar to that for the synthesis of TpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2]Cl was followed, except that n-BuN-ACHTUNGTRENNUNG(PPh2)2 (1.1 g, 2.5 mmol) was used in place of 4-CF3C6H4N-ACHTUNGTRENNUNG(PPh2)2. Yellow solid; yield: 1.29 g (72%); anal. calcd. (%)for C37H39BClN7P2Ru: C 56.18, H 4.97, N 12.39; found: C55.96, H 5.05, N 12.17; IR (KBr): n(B�H) =2462 cm�1 (br);1H NMR (400.13 MHz, CDCl3, 25 8C): d=8.04–8.05 (m, 4 H,PPh2-H), 7.68 (s, 2 H, Tp-H), 7.62 (s, 2 H, Tp-H), 7.39–7.44(m, 6 H, PPh2-H), 7.38 (d, 1 H, Tp-H), 7.19–7.23 (m, 6 H,PPh2-H), 7.09–7.11 (m, 4 H, PPh2-H), 6.14 (s, 2 H, Tp-H),5.81 (d, 1 H, Tp-H), 5.17 (t, 1 H, Tp-H), 3.44 (m, 2 H,-NCH2-), 1.44 (m, 2 H, -NCH2CH2-), 1.01 (m, 2 H,-NCH2CH2CH2-), 0.67 (t, 3 H, -NCH2CH2CH2CH3);31P{1H} NMR (161.7 MHz, CDCl3, 25 8C): d=82.97 (s); ESI-MS: m/z =791, [M]+.

TpRu ACHTUNGTRENNUNG[n-BuN ACHTUNGTRENNUNG(CH2PPh2)2]Cl

A procedure similar to that for the synthesis of TpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2]Cl was followed, except that n-BuN-ACHTUNGTRENNUNG(CH2PPh2)2 (1.2 g, 2.5 mmol) was used in place of 4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2. Yellow solid; yield: 1.19 g (63%); anal.calcd. (%) for C39H43BClN7P2Ru: C 57.19, H 5.29, N 11.97;found: C 57.03, H 5.34, N 11.85; IR (KBr) :n(B�H) =2459 cm�1 (br); 1H NMR (400.13 MHz, C6D6, 25 8C): d= 8.45(m, 4 H, PPh2-H), 7.64 (s, 2 H, Tp-H), 7.59 (s, 2 H, Tp-H),7.34 (d, 1 H, Tp-H), 7.19–7.30 (m, 6 H, PPh2-H), 6.88–6.94(m, 10 H, PPh2-H), 5.84 (s, 2 H, Tp-H), 5.73 (d, 1 H, Tp-H),5.04 (t, 1 H, Tp-H), 3.86 (m, 2 H, -NCH2-), 3.63 (m, 2 H,PPh2PCH2-), 2.56 (t, 2 H, PPh2PCH2-), 1.36 (m, 2 H,-NCH2CH2-), 1.23 (m, 2 H, -NCH2CH2CH2-), 0.94 (t, 3 H,-NCH2CH2CH2CH3); 31P{1H} NMR (161.7 MHz, C6D6,25 8C): d=34.82 (s); ESI-MS: m/z=819, [M]+.

TpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2] ACHTUNGTRENNUNG(OTf) (I)

To the complex TpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2]Cl (1.0 g,1.14 mmol) and silver triflate (0.36 g, 1.4 mmol) was addedfreshly degassed THF (20 mL); the resulting mixture was re-fluxed with stirring for 4 h. At the end of this period, themixture was cooled to room temperature and evaporated todryness under reduced pressure. The residue was extractedwith dichloromethane (2� 10 mL). The insoluble materialwas filtered out. The solvent of the filtrate was removedunder reduced pressure and a yellow paste was obtained.Hexane (5 mL) was added to the residue, with stirring, toproduce a yellow solid. The solid was filtered out andwashed with hexane/ethanol (1:1, 2 � 10 mL). It was thencollected and dried under vacuum at room temperature;yield: 0.81 g (72%); anal. calcd. (%) ofC41H34BF6N7O3P2RuS: C 49.61, H 3.45, N 9.88; found: C49.80, H 3.57, N 9.60; IR (KBr): n(B�H) = 2468 cm�1 (br);1H NMR [400.13 MHz, (CD3)2CO, 25 8C]: d=8.08 (s, 2 H,Tp-H), 7.99–7.98 (m, 4 H, PPh2-H), 7.70–7.69 (m, 6 H, PPh2-H), 7.67 (d, 1 H, Tp-H), 7.52 (d, 2 H, 4-CF3C6H4N-), 7.46–7.45 (m, 6 H, PPh2-H), 7.32–7.30 (m, 4 H, PPh2-H), 7.21 (d,2 H, 4-CF3C6H4N-), 6.99 (s, 2 H, Tp-H), 6.33 (d, 2 H, Tp-H),5.20 (d, 1 H, Tp-H), 5.19 (t, 1 H, Tp-H); 31P{1H} NMR[161.7 MHz, (CD3)2CO, 25 8C]: d=85.90 (s); ESI-MS: m/z =844.22 [M�OTf]+.ACHTUNGTRENNUNG{TpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2]CH3CN}+OTf� (II)

THF/acetonitrile (20:1, 20 mL) was added to the complexTpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2]Cl (1.0 g, 1.14 mmol) and silvertriflate (0.36 g, 1.4 mmol); the resulting mixture was re-fluxed with stirring for 4 h. At the end of this period, themixture was cooled to room temperature and evaporated todryness under reduced pressure. The residue was extractedwith dichloromethane (2� 10 mL). The insoluble materialwas filtered out. The solvent of the filtrate was removedunder reduced pressure and a yellow paste was obtained.Hexane (5 mL) was added to the residue, with stirring, toproduce a yellow solid. The solid was filtered out andwashed with hexane/ethanol (1:1, 2 � 10 mL). It was thencollected and dried under vacuum at room temperature;yield: 0.77 g (66%); anal. calcd (%) forC43H37BF6N8O3P2RuS: C 49.96, H 3.61, N 10.84; found: C49.60, H 3.71, N 10.56; IR (KBr): n(B�H) =2487 (br);




1H NMR (400.13 MHz, CD3CN, 25 8C): d= 7.89 (s, 2 H, Tp-H), 7.83–7.84 (m, 4 H, PPh2-H), 7.74 (s, 2 H, Tp-H), 7.72–7.74 (m, 4 H, PPh2-H), 7.56 (d, 1 H, Tp-H), 7.41 (t, 4 H,PPh2-H), 7.28 (q, 4 H, PPh2-H), 7.13–7.27 (m, 4 H, PPh2-H),7.13–7.27 (m, 4 H, 4-CF3C6H4N-), 6.32 (t, 2 H, Tp-H), 5.31(d, 1 H, Tp-H), 5.20 (t, 1 H, Tp-H), 2.07 (s, 3 H, NCCH3);31P{1H} NMR (161.7 MHz, CD3CN, 25 8C): d= 87.05 (s);ESI-MS: m/z= 885 [M]+.

TpRu ACHTUNGTRENNUNG[n-BuN ACHTUNGTRENNUNG(PPh2)2] ACHTUNGTRENNUNG(OTf) (III)

A procedure similar to that for the synthesis of TpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2]OTf was followed, except that TpRu ACHTUNGTRENNUNG[n-BuN ACHTUNGTRENNUNG(PPh2)2]Cl (0.90 g, 1.14 mmol) was used in place ofTpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2]Cl. Yellow solid; yield: 0.84 g(67%); anal. calcd. (%) for C38H39BF3N7O3P2RuS: C 50.45,H 4.35, N 10.84; found: C 50.19, H 4.41, N 10.61; IR (KBr):n(B�H) = 2478 cm�1 (br); 1H NMR (400.13 MHz, CDCl3,25 8C): d=7.77 (d, 2 H, Tp-H), 7.74 (m, 4 H, PPh2-H), 7.62(s, 2 H, Tp-H), 7.47–7.53 (m, 6 H, PPh2-H), 7.28 (t, 2 H,PPh2-H), 7.17 (s, 1 H, Tp-H), 7.11–7.17 (m, 8 H, PPh2-H),6.21 (s, 2 H, Tp-H), 5.82 (s, 1 H, Tp-H), 5.13 (s, 1 H, Tp-H),3.50 (m, 2 H, -NCH2-), 1.52 (m, 2 H, -NCH2CH2-), 1.06 (m,2 H, -NCH2CH2CH2-), 0.70 (t, 3 H, -NCH2CH2CH2CH3);31P{1H} NMR (161.7 MHz, CDCl3, 25 8C): d=83.32 (s); ESI-MS: m/z =755, [M�OTf]+.ACHTUNGTRENNUNG{TpRuACHTUNGTRENNUNG[n-BuN ACHTUNGTRENNUNG(PPh2)2]CH3CN}+OTf� (IV)

A procedure similar to that for the synthesis of {TpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2]CH3CN]+OTf� was followed, except thatTpRu ACHTUNGTRENNUNG[n-BuN ACHTUNGTRENNUNG(PPh2)2]Cl (0.90 g, 1.14 mmol) was used inplace of TpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2]Cl. Yellow solid; yield:0.81 g (69%); anal. calcd. (%) for C40H42BF3N8O3P2RuS: C50.80, H 4.48, N 11.85; found: C 50.64, H 4.60, N 11.65; IR(KBr): n(B�H) =2495 cm�1 (br); 1H NMR (400.13 MHz,CDCl3, 25 8C): d=7.79 (s, 2 H, Tp-H), 7.59–7.68 (m, 10 H,PPh2-H), 7.59–7.68 (d, 1 H, Tp-H), 7.34 (t, 2 H, PPh2-H),7.23 (s, 2 H, Tp-H), 7.12–7.16 (m, 4 H, PPh2-H), 7.02–7.03(m, 4 H, PPh2-H), 6.28 (d, 1 H, Tp-H), 6.24 (s, 2 H, Tp-H),5.49 (t, 1 H, Tp-H), 3.74 (m, 2 H, -NCH2-), 2.09 (s, 3 H,NCCH3), 1.63 (m, 2 H, -NCH2CH2-), 1.22 (m, 2 H,-NCH2CH2CH2-), 0.81 (t, 3 H, -NCH2CH2CH2CH3);31P{1H} NMR (161.7 MHz, CDCl3, 25 8C): d=83.81 (s). ESI-MS: m/z =797 [M]+.ACHTUNGTRENNUNG{TpRuACHTUNGTRENNUNG[n-BuN ACHTUNGTRENNUNG(CH2PPh2)2]CH3CN}+OTf� (V)

A procedure similar to that for the synthesis of {TpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2]CH3CN}+OTf� was followed, except thatTpRu ACHTUNGTRENNUNG[n-BuN ACHTUNGTRENNUNG(CH2PPh2)2]Cl (0.90 g, 1.14 mmol) was used inplace of TpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2]Cl. Yellow solid; yield:0.73 g (61%); anal. calcd. (%) for C42H46BF3N8O3P2RuS: C51.81, H 4.76, N 11.51; found: C 51.88, H 4.88, N 11.26; IR(KBr): n(B�H) =2484 cm�1 (br); 1H NMR (400.13 MHz,CDCl3, 25 8C): d=7.90 (d, 1 H, Tp-H), 7.84 (s, 2 H, Tp-H),7.67 (m, 4 H, PPh2-H), 7.52–7.58 (m, 4 H, PPh2-H), 7.33–7.47(m, 2 H, PPh2-H), 7.21 (t, 2 H, PPh2-H), 7.19 (s, 2 H, Tp-H),6.96 (t, 4 H, PPh2-H), 6.92 (d, 1 H, Tp-H), 6.35 (m, 4 H,PPh2-H), 6.11 (s, 2 H, Tp-H), 5.79 (t, 1 H, Tp-H), 4.11 (m,2 H, -NCH2-), 3.34 (m, 2 H, PPh2PCH2-), 3.04 (t, 2 H,PPh2PCH2-), 1.65 (m, 2 H, -NCH2CH2-), 1.56 (s, 3 H,NCCH3), 1.40 (m, 2 H, -NCH2CH2CH2-), 0.97 (t, 3 H,

-NCH2CH2CH2CH3); 31P{1H} NMR (161.7 MHz, CDCl3,25 8C): d= 31.01 (s); ESI-MS: m/z= 825 [M]+; 784 [M�NCCH3]

+

Preparation of Complexes Ia, Ib and Id

The vinylidene complex Ia was readily prepared by reactingI with excess phenylacetylene in chloroform at 60 8C. Themost relevant spectroscopic feature of Ia is the characteristicdeshielded 13C{1H} NMR signal for the a-carbon of the vi-nylidene moiety at d= 375.7 ppm; the Cb resonance fallswithin the aromatic region and is therefore masked by alarge number of signals. The vinylidene proton of Ia can bereadily identified as a triplet at d=4.51 ppm in the 1H NMRspectrum. 31P{1H} NMR spectroscopy shows a singlet at d=75.9 ppm, which is consistent with the chemical equivalenceof the two phosphorus atoms of the diphosphinoamineligand. Similar to other reported diphosphinoamino com-plexes, the 31P NMR signal of Ia is considerably deshieldedcompared to that of the free ligand. Complex Ib was con-veniently prepared by deprotonation of Ia with NaOH inethanol. The Ca of the alkynyl moiety appear as a triplets atd= 121.6 ppm (JCP =30 Hz) in the 13C{1H} NMR spectrum.31P{1H} NMR spectroscopy shows a singlet at d= 90.7 ppmattributable to the equivalent phosphorus atoms. ComplexId, although it is obtainable via reaction of Ia with water,was prepared more conveniently by an alternative method –reaction of I with pressurized CO. Complex Id is conven-iently characterized by NMR and IR spectroscopy:13C{1H} NMR, a singlet, which is due to the carbonyl carbon,is detected at d=201.1 ppm; 31P{1H} NMR, a singlet corre-sponding to the equivalent phosphorus atoms of the diphos-phinoamine ligand, is seen at d= 80.7 ppm; IR spectroscopyshows the u(C�O) absorption at 1995 cm�1. Complexes I, Ia,Ib and Id were subject to X-ray diffraction studies. CCDC755811 (I), CCDC 755812 (Ia), CCDC 755813 (Ib) andCCDC 755814 (Id) contain the supplementary crystallo-graphic data for the compounds of this paper. These datacan be obtained free of charge from The Cambridge Crystal-lographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.ACHTUNGTRENNUNG{TpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2]ACHTUNGTRENNUNG(=C=CHPh)]+OTf� (Ia)

The complex TpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2]OTf (0.5 g,0.5 mmol) was dissolved in freshly degassed chloroform(10 mL) and treated with 3 equiv. of phenylacetylene(0.16 mL, 1.50 mmol). The resulting solution was heated at60 8C for 16 h. At the end of this period, the solution wascooled to room temperature and evaporated to drynessunder reduced pressure to yield a pink paste. Hexane(5 mL) was added to the residue, with stirring, to produce apink solid. The solid was filtered out and washed withhexane/ethanol (3:2, 2 � 5 mL). It was collected and driedunder vacuum at room temperature; yield: 0.43 g (78%);anal. calcd. (%) for C49H40BF6N7O3P2RuS: C 53.76, H 3.68,N 8.96; found: C 53.64, H 3.79, N 8.84; IR (KBr): n(B�H) =2486 (br), n(C=C) =1663 cm�1 (s); 1H NMR (400.13 MHz,CDCl3, 25 8C): d=7.83 (s, 2 H, Tp-H), 7.79–7.80 (m, 4 H,PPh2-H), 7.64 (t, 3 H, PPh2-H), 7.50 (s, 2 H, Tp-H), 7.48 (s,1 H, Tp-H), 7.46–7.50 (m, 4 H, PPh2-H), 7.39 (d, 2 H, 4-CF3C6H4N-), 7.24 (t, 3 H, =C=CHPh-H), 7.08–7.23 (m, 10 H,PPh2-H), 7.01 (d, 2 H, 4-CF3C6H4N-), 6.51 (d, 2 H, =C=




CHPh-H), 6.34 (s, 2 H, Tp-H), 5.49 (d, 1 H, Tp-H), 5.36 (t,1 H, Tp-H), 4.50 (t, 1 H, =C=CHPh); 31P{1H} NMR(161.7 MHz, CDCl3, 25 8C): d= 76.01 (s); 13C{1H} NMR(100.61 MHz, CDCl3, 25 8C): d=375.74 (t, JP,C = 18.1 Hz, =C=CHPh); ESI-MS: m/z= 945.30, [M�PhC�CH]+.

TpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2] ACHTUNGTRENNUNG(C�CPh) (Ib)

Freshly degassed ethanol (10 mL) was added to the complex{TpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2] ACHTUNGTRENNUNG(=C=CHPh)]OTf (0.5 g,0.45 mmol) and NaOH (0.09 g, 2.30 mol); the resulting mix-ture was stirred at room temperature for 30 min. At the endof this period, the solvent of the mixture was removedunder reduced pressure. The residue was extracted with tol-uene (2� 10 mL). The insoluble material was filtered out.The solvent of the filtrate was removed under reduced pres-sure and a yellow paste was obtained. Hexane (5 mL) wasadded to the residue, with stirring, to produce a yellowsolid. The solid was filtered out and washed with hexane/ethanol (3:2, 2 � 5 mL). It was then collected and driedunder vacuum at room temperature; yield: 0.23 g (55%);anal. calcd. (%) for C48H39BF3N7P2Ru: C 61.03, H 4.16, N10.38; found: C 61.17, H 4.31, N 10.16; IR (KBr): n(B�H) 2480(br), n(C�C) =2086 cm�1 (vs); 1H NMR (400.13 MHz, CDCl3,25 8C): d=8.49–8.51 (m, 4 H, PPh2-H), 7.78 (s, 2 H, Tp-H),7.60–7.62 (m, 4 H, PPh2-H), 7.49 (s, 2 H, Tp-H), 7.49 (s, 1 H,Tp-H), 7.44 (d, 2 H, 4-CF3C6H4N-), 7.25 (m, 4 H, PPh2-H),7.17 (q, 3 H, -C�CPh-H), 7.08 (m, 2 H, -C�CPh-H), 7.07 (d,2 H, 4-CF3C6H4N-), 6.94 (m, 4 H, PPh2-H), 6.88 (m, 4 H,PPh2-H), 5.92 (d, 2 H, Tp-H), 5.41 (d, 1 H, Tp-H), 5.40 (t,1 H, Tp-H); 31P{1H} NMR (161.7 MHz, CDCl3, 25 8C): d=90.66 (s); 13C{1H} NMR (100.61 MHz, CDCl3, 25 8C): d=121.56 (t, JP,C = 30 Hz, -C�CPh); ESI-MS: m/z =945.32 [M]+.ACHTUNGTRENNUNG{TpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2](CO)}+OTf� (Id)

The reaction was carried out in a 250-mL stainless steel au-toclave. The complex TpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2]OTf (0.5 g,0.5 mmol) was dissolved in freshly degassed chloroform(10 mL). The solution was heated under 5 bar of CO at120 8C for 30 min. At the end of this period, the mixture wascooled to room temperature and evaporated to drynessunder reduced pressure to yield a white paste. Hexane(5 mL) was added to the residue, with stirring, to produce awhite solid. The solid was filtered out and washed with di-ethyl ether (2 � 5 mL). It was collected and dried undervacuum at room temperature; yield: 0.41 g (80%); anal.calcd. (%) for C42H34BF6N7O4P2RuS: C 49.43, H 3.36, N9.61; found: C 50.15, H 3.49, N 9.44; IR (KBr): n(B�H) = 2525(br), u(C�O) = 1995 cm�1 (vs); 1H NMR (400.13 MHz, CDCl3,25 8C): d=7.81 (s, 2 H, Tp-H), 7.77–7.79 (m, 10 H, PPh2-H),7.50 (d, 1 H, Tp-H), 7.46–7.50 (t, 2 H, PPh2-H), 7.40 (d, 2 H,4-CF3C6H4N-), 7.24–7.28 (m, 4 H, PPh2-H), 7.11–7.15 (m,4 H, PPh2-H), 7.13 (s, 2 H, Tp-H), 6.94 (d, 2 H, 4-CF3C6H4N-), 6.31 (s, 2 H, Tp-H), 5.43 (d, 1 H, Tp-H), 5.35 (t, 1 H, Tp-H); 31P{1H} NMR (161.7 MHz, CDCl3, 25 8C): d=80.66 (s);13C{1H} NMR (100.61 MHz, CDCl3, 25 8C): d=201.06 (t,JP,C = 14.7 Hz, -C�O); ESI-MS: m/z =872.24 [M]+.

General Procedure for TpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2](OTf) (I)-Catalyzed Addition of b-Diketones to 1-Alkynes

The reactions were carried out in 11-mm Schlenk tubesequipped with Teflon screw caps. (The reactions in Table 2,entries 7–9, 11, 13 were carried out in 5-mm pressure-valvedNMR tubes under 10 bar of argon). In a typical run, rutheni-um complex (0.005 mmol, 0.4 mol%) was loaded into thetube; the system was evacuated and filled with nitrogen forfour cycles. b-Diketones (1.25 mmol) and terminal alkynes(1.50 mmol) were then added to the tube via syringes andneedles. The tube was heated in a silicon oil bath at 120 8C.At the end of the specific period, the product was isolatedby flash column chromatography on silica gel or by prepara-tive thin layer chromatography (silica gel). The organicproducts 3b, 3c, 3d, 3e, 3f, 3g, 3h and 3k are new com-pounds; they were characterized by 1H, 13C{1H} NMR spec-troscopy, mass spectrometry and HR-MS analysis.

NMR Monitoring of TpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2]OTf(I)-Catalyzed Addition of b-Diketones to 1-Alkynes

The reactions were carried out in 11-mm Schlenk tubesequipped with Teflon screw caps. Ruthenium complexTpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2]ACHTUNGTRENNUNG(OTf) (0.005 mmol, 0.40 mol%)was loaded into each of the eight tubes equipped with mag-netic stirrers. The tubes were evacuated and filled with ni-trogen for four cycles. Acetylacetone (1.25 mmol) and phe-nylacetylene (1.50 mmol) were then added to each tube viasyringes and needles. The tubes were sealed with the screwcaps and heated in a silicon oil bath at 120 8C. At differenttime intervals, a tube was withdrawn from the silicon oilbath and rapidly cooled down to room temperature; 1H, 19Fand 31P{1H} NMR spectra of the mixture were taken. Therelative concentrations of the species present were obtainedby comparing the integrations of their signals in the31P{1H} NMR spectra. Conversion of the reaction was ob-tained by measuring the integrations of the characteristicpeaks of the products with reference to distinct peaks of un-reacted acetylacetone in the 1H NMR spectrum.

General Procedure for TpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2]OTf (I)-Catalyzed Hydroamination of TerminalAlkynes with Secondary Amines

The reactions were carried out in 11-mm Schlenk tubesequipped with Teflon screw caps. In a typical run, rutheniumcomplex TpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2]OTf (0.01 mmol,1.00 mol%) was loaded into the tube. The tube was evacuat-ed and filled with nitrogen for four cycles. Methanol(0.10 mL), secondary amine (1.0 mmol) and terminal alkyne(1.2 mmol) were then added to the tube via syringes andneedles. The tube was sealed with the screw cap and the so-lution was stirred in a silicon oil bath at 120 8C for 24 h. Atthe end of this period, the tube was cooled to room temper-ature and 25 mL of 1,1,2,2-tetrachloroethane were added asinternal standard; a 0.1 mL aliquot of the solution was re-moved and analyzed by 1H NMR spectroscopy (in C6D6).Conversion of the reaction was obtained by measuring theintegrations of the characteristic peaks of the products withreference to distinct peaks of the internal standard. The or-ganic products described in Table 3 are known compounds




and were characterized by comparing their 1H NMR datawith the reported ones.

NMR Monitoring of TpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2]OTf(I)-Catalyzed Hydroamination of Phenylacetylenewith Diethylamine

The reaction was carried out in a 5-mm NMR pressure-valved NMR tube. The ruthenium complex TpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2]OTf (0.01 mmol, 1.00 mol%) was loadedto the tube; it was evacuated and filled with nitrogen forfour cycles. CD3OD (0.1 mL), diethylamine (1.0 mmol) andphenylacetylene (1.2 mmol) were then added to the tube viasyringes and needles. The tube was heated in a silicon oilbath at 120 8C under 10 bar of argon. At different time inter-vals, the NMR tube was rapidly cooled down to room tem-perature and 1H and 31P{1H} NMR spectra of the solutionwere taken. The relative concentrations of the species pres-ent were obtained by comparing the integrations of theirsignals in the 31P{1H} NMR spectra. Conversion of the reac-tion was obtained by measuring the integrations of the char-acteristic peaks of the products with reference to distinctpeaks of unreacted diethylamine in the 1H NMR spectrum.

3-(1-Hydroxyethylidene)-4-(4-methoxyphenyl)pent-4-en-2-one (3b): Pale yellow oil; 1H NMR (400 MHz, CDCl3): d=16.66 (s, 1 H, enol-OH), 7.35 (d, J=9 Hz, 2 H, 4-OCH3C6H4-), 6.85 (d, J= 9 Hz, 2 H, 4-OCH3C6H4-), 5.78 (s, 1 H, -C=CH2), 5.10 (s, 1 H, -C=CH2), 3.77 (s, 3 H, 4-OCH3C6H4-),

1.96 (s, 6 H, methyl-CH3); 13C{1H} NMR (100 MHz, CDCl3):d= 191.52, 160.09, 143.26, 132.55, 127.51, 116.53, 114.42,114.38, 55.51, 23.798; HR-MS (+ESI): m/z=233.1171, calcd.for C14H16O3 [M+ H]+: 232.1099.

4-Hydroxy-3-(1-p-tolylvinyl)pent-3-en-2-one (3c): Paleyellow oil; 1H NMR (400 MHz, CDCl3): d=16.73 (s, 1 H,enol-OH), 7.38 (d, J=8 Hz, 2 H, 4-CH3C6H4-), 7.18 (d, J=8 Hz, 2 H, 4-CH3C6H4-), 5.91 (s, 1 H, -C=CH2), 5.21 (s, 1 H,-C=CH2), 2.38 (s, 3 H, 4-CH3C6H4-), 2.02 (s, 6 H, methyl-CH3); 13C{1H} NMR (100 MHz, CDCl3): d=191.59, 143.78,138.43, 137.26, 129.86, 126.29, 117.74, 114.37, 23.90, 21.48;HR-MS (+ESI): m/z=217.1227, calcd. for C14H16O2 [M+H]+: 216.2756.

3-[1-(4-Bromophenyl)vinyl]-4-hydroxypent-3-en-2-one(3d): Pale yellow oil; 1H NMR (400 MHz, CDCl3): d= 16.84(s, 1 H, enol-OH), 7.56 (d, J=8 Hz, 2 H, 4-BrC6H4-), 7.44 (d,J=8 Hz, 2 H, 4-BrC6H4-), 6.04 (s, 1 H, -C=CH2), 5.39 (s, 1 H,-C=CH2), 2.08 (s, 6 H, methyl-CH3); 13C{1H} NMR(100 MHz, CDCl3): d=191.71, 143.14, 139.31, 132.47, 128.18,122.85, 119.68, 113.90, 24.12; HR-MS (+ESI): m/z=281.0188, calcd. for C13H13BrO2 [M]+: 281.1451.

3-[1-(4-Fluorophenyl)vinyl]-4-hydroxypent-3-en-2-one(3e): Pale yellow oil; 1H NMR (400 MHz, CDCl3): d= 16.66(s, 1 H, enol-OH), 7.38 (dd, J=6, 8 Hz, 2 H, 4-FC6H4-), 6.97(t, J= 8 Hz, 2 H, 4-FC6H4-), 5.81 (s, 1 H, -C=CH2), 5.18 (s,1 H, -C=CH2), 1.93 (s, 6 H, methyl-CH3); 13C ACHTUNGTRENNUNG{1H NMR(100 MHz, CDCl3): d=191.62, 164.38, 161.92, 142.99, 136.36,128.09, 118.55, 116.12, 115.91, 114.13, 23.84; HR-MS (+

Table 3. TpRu[4-CF3C6H4N ACHTUNGTRENNUNG(PPh2)2] ACHTUNGTRENNUNG(OTf) (I)-catalyzed hydroamination of 1-alkynes with sec-ondary amines.[a]

[a] Reaction conditions: catalyst (0.01 mmol), secondary amine (1 mmol), terminal alkyne(1.2 mmol); in 0.1 mL MeOH, 120 8C, 24 h.

[b] Conversion determined by 1H NMR spectroscopy with 1,1,2,2-tetrachloroethane as an in-ternal standard.

[c] 48 h.




ESI): m/z=221.0975, calcd. for C13H13FO2 [M+H]+:220.2395.

4-Hydroxy-3-(1-(thiophen-3-yl)vinyl)pent-3-en-2-one (3f):Pale yellow oil; 1H NMR (400 MHz, CDCl3): d=16.59 (s,1 H, enol-OH), 7.08 (m, 1 H, thiophene-H), 7.25–7.29 (m,1 H, thiophene-H), 7.29–7.33 (m, 1 H, thiophene-H), 5.81 (s,1 H, -C=CH2), 5.15 (s, 1 H, -C=CH2), 2.00 (s, 6 H, methyl-CH3); 13C{1H} NMR (100 MHz, CDCl3): d=191.57, 142.85,139.00, 127.12, 125.52, 122.97, 117.52, 114.51; HR-MS (+ESI): m/z=209.0639, calcd. for C11H12O2S [M+H]+:208.2768.

3-(1-Cyclopentylideneethyl)-4-hydroxypent-3-en-2-one(3g): Pale yellow oil; 1H NMR (400 MHz, CDCl3): d= 16.12(s, 1 H, enol-OH), 2.11 (m, 2 H, cyclopentyl-CH2), 1.82 (m,2 H, cyclopentyl-CH2), 1.79 (s, 6 H, methyl-CH3), 1.59 (s,6 H, methyl-CH3), 1.53 (m, 2 H, cyclopentyl-CH2), 1.44 (m,2 H, cyclopentyl-CH2); 13C{1H} NMR (100 MHz, CDCl3): d=190.29, 144.85, 121.53, 116.12, 32.41, 30.97, 27.21, 22.98,21.18; HR-MS (+ESI): m/z=195.1384, calcd. for C12H18O2

[M+H]+: 194.2701.3-(1-Hydroxyethylidene)-4,7-dimethyloct-4-en-2-one (3h):

Pale yellow oil; 1H NMR (400 MHz, CDCl3): d=16.46 (s,1 H, enol-OH), 5.54 (t, J=7 Hz,1 H, =CHCH2-), 1.99 (s, 6 H,methyl-CH3), 1.83 (s, 3 H, methyl-CH3), 1.74 (t, J= 7 Hz,2 H, =CHCH2-), 1.61 [m, 1 H, -CHACHTUNGTRENNUNG(CH3)2], d 0.86 [d, J=6 Hz, 6 H, -CH ACHTUNGTRENNUNG(CH3)2]; 13C{1H} NMR (100 MHz, CDCl3):d= 190.77, 132.28, 131.98, 113.46, 39.14, 29.00, 25.82, 23.49,23.27; HR-MS (+ ESI): m/z=197.1543, calcd. for C12H20O2

[M+H]+: 196.286.4-Hydroxy-6-methyl-3-(1-phenylvinyl)heptan-2-one (3k):

Pale yellow oil; 1H NMR (400 MHz, CDCl3): d=17.17 (s,1 H, enol-OH), 7.66 (d, J= 7 Hz, 2 H, Ph-H), 7.54 (t, J=7 Hz, 2 H, Ph-H), 7.49 (m, 1 H, Ph-H), 6.14 (s, 1 H, -C=CH2),5.43 (s, 1 H, -C=CH2), 2.49 [m, 1 H, -CH2CH ACHTUNGTRENNUNG(CH3)2], 2.33[m, 2 H, -CH2CH ACHTUNGTRENNUNG(CH3)2], 2.20 (s, 3 H, methyl-CH3), 1.03–1.71 [m, 6 H, -CH2CH ACHTUNGTRENNUNG(CH3)2]; 13C{1H} NMR (100 MHz,CDCl3): d=193.00, 192.68, 143.72, 140.28, 129.09, 128.55,126.27, 118.89, 114.48, 44.79, 26.17, 24.31, 22.93; HR-MS(+ESI): m/z=245.1540, calcd. for C16H20O2 [M+H]+:244.3288.

Acknowledgements

We acknowledge financial support from the Research GrantCouncil of Hong Kong (Project Nos. PolyU 5006/07P, PolyU5011/08P).

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Hydro(trispyrazolyl)borato-Ruthenium(II) Diphosphinoamino Complex-Catalyzed Addition of b-Diketones...

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