New Approach to Vinylphosphines Based on Pd- and Ni-Catalyzed Diphenylphosphine Addition to Alkynes

Abstract

The catalytic addition of Ph 2 PH to phenylacetylene regioselectively leads to the Ph 2 P-CH=CHPh isomer with Pd(PPh 3 ) 4 in acetonitrile and to the Ph 2 P-C(Ph)=CH 2 isomer with Ni(acac) 2 / (EtO) 2 P(O)H in benzene. High selectivity were also obtained for the catalytic addition of Ph 2 PH to t BuCºCH and to PhCºCPh.Alkenylphosphines, including functionalized derivatives, are attracting current interest as useful ligand to control the activation of various substrates within their transition metal complexes. 1 They also have potential for the access to a wide variety of functional ligands via modification of their C=C bond including via enantioselective catalysis. 2 However, their use is still limited due to the lack of simple and straightforward routes to alkenylphosphines. Standard syntheses of vinylphosphines involve the reaction of vinylmagnesium or lithium derivatives with halophosphines 3 and the addition of primary or secondary phosphines to alkynes. 4 The first method can not be applied to the synthesis of vinylphosphines with functional groups and the second method usually gives a mixture of isomers. Functionalized diphenylvinylphosphines have conveniently been prepared recently via addition of phosphorous(III)-halides to electron-rich alkynes 5 and via catalytic cross-coupling reactions of functional α-and β-alkenylbromides and chlorides with diphenylphosphine. 6 The preparation of vinylphosphines on thermal reaction of phosphines R 2 PH with alkynes require severe conditions, prolonged heating and lead to product mixtures with moderate yields. 7Whereas transition metal complex catalyzed hydrosilylation, 8 hydrostannylation 9 and hydroboration 10 of alkynes are well developed, their catalytic hydrophosphination reaction of alkynes, to the best of our knowledge, is not described. 11 Recently, organolanthanide-catalyzed intramolecular hydrophosphination-cyclization of phosphinoalkynes has been reported. 12 Here we wish to report a new approach to diphenylvinylphosphines based on direct catalytic addition of Ph 2 PH to alkynes promoted by palladium and nickel catalyst precursors. 13The catalytic addition of diphenylphosphine to terminal alkynes 1 is expected to produce three types of alkenylphosphines via addition of the phosphorous atom to the substituted (2) or terminal (3) alkyne carbon atom, the latters having the Z or E configuration (Eq. 1). Equation 1The catalytic addition of diphenylphosphine to phenylacetylene 1a was attempted with a variety of Pd(0), Pd(II), Ni(0) and Ni(II) precursors and quantitative yields and high regio-and stereoselectivities were obtained. The results are presented in Table 1 and show that the regioselectivity of hydrophosphination depends dramatically on the nature of the catalyst. Conversions were monitored by 31 P NMR of Ph 2 PH. It is noteworthy that under the same conditions without catalyst only traces of the products were observed if any.The reactions catalyzed by the complexes Pd(PPh 3 ) 4 and Pd(dba) 2 lead to the isomer 3a as the only product in acetonitrile (en...

Hydrophosphination of alkynes and related reactions catalyzed by rare-earth amides

“…As a result, the empirical rate law can be described as v = k [catalyst] 2 [alkyne] 1 [phosphine] 0 at least under standard conditions, indicating that the complex 1 should be changed to some dimeric Yb species in the mixture.…”

“…However, application of this procedure was limited to pentavalent phosphorous compounds such as (RO) 2 P(O)H and Ph 2 P(O)H, and the reaction of trivalent phosphine was generally unsuccessful [2]. Trivalent lanthanocenes were also found to exhibit high catalyst activity in the intramolecular hydrophosphination of phosphino-alkynes and alkenes [3].…”

Contribution of I. P. Beletskaya in the Twentieth Year Successful Russian-French Cooperation in Catalytic Syntheses

“…Very high regioselectivity was also observed in the catalytic addition of Ph 2 PH to tertbutylacetylene and tolane (Scheme 2). [3] In all cases near to quantitative yields of the addition products were obtained.…”

Reaction of Alkynes

“…The addition of diphenylphosphine to alkynes occurs with various palladium and nickel catalysts to yield the alkenylphosphines, both regio-and stereoselectively [21]. In a particular reaction shown in Table 4 [24].…”