Palladium-Catalyzed Hydrophosphinylation of Alkynes

Stoichiometric reactions provided information on the mechanism of catalysis. Two equivalents of PH(0)Ph2 reacted with M(PEt3)j (M = Pd, Pt) to give cis- 

NMR monitoring of the reaction of the palladium complex with 1-octyne suggested that the alkyne inserts into the Pd-H bond. Further heating produced a mixture of the two regioisomeric alkenylphosphine oxides, the anti-Markovnikov adduct being the favored product (54 46, 65% yield). 

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Scheme 5-22 Stoichiometric reactions relevant to the proposed mechanism for palladium-catalyzed hydrophosphinylation of alkynes...

Deprele S, Montchamp J-L (2002) Palladium-catalyzed hydrophosphinylation of alkenes and alkynes. J Am Chem Soc 124 9386-9387... 

Scheme5-24 Eq. (1) Proposed mechanism for Eq. (2) Stoichiometric reactions relevant to the phosphinic acid-modified palladium-catalyzed proposed mechanism hydrophosphinylation of alkynes.

Han, L.-B., Choi, N., and Tanaka, M., Oxidaative addition of HP(0)Ph2 to platinum(O) and palladium(O) complexes and palladium-catalyzed regio- and stereoselective hydrophosphinylation of alkynes, Organometallics, 15, 3259,... 

Han L-B, Zhao C-Q, Onozawa S-y, Goto M, Tanaka M. Retention of configuration on the oxidative addition of P—H bond to platinum(O) complexes the first straightforward synthesis of enantiomerically pure P-chiral alkenylphosphinates via palladium-catalyzed stereospecific hydrophosphinylation of alkynes. J. Am. Chem. Soc. 2002 124 3842-3843. 

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