Alkynes intermolecular hydrophosphination

Recently, intermolecular hydrophosphination of alkynes was also reported with ytterbium-imine complex catalyst precursors [20]. Aromatic alkynes react at room temperature to afford ( )-isomers, while aliphatic ones require heating at 80 °C and, quite surprisingly, (Z)-isomers (trans-addition products) are formed preferentially (Table 4). In this respect the ytterbium-catalyzed reactions are different from the radical process, in which the ( )-isomer formed initially isomerizes to the (Z)-isomer. 

Table 4 Ytterbium-catalyzed intermolecular hydrophosphination of alkynes 1) " YbCHIVIPAle...

Organolanthanide-catalyzed intermolecular hydrophosphination is a more facile process than intermolecular hydroamination. The reaction of alkynes, dienes, and activated alkenes with diphenylphosphine was achieved utilizing the ytterbium imine complex 9 (Fig. 8) as catalyst [185-188]. Unsymmetric internal alkynes react regioselectively, presumably due to an aryl-directing effect (48) [186]. 

Intermolecular Hydrophosphination of Activated Alkenes, Alkynes, and Diynes... 

Takaki K, Takeda M, Koshoji G, Shishido T, Takehira K (2001) Intermolecular hydrophosphination of alkynes and related carbon—carbon multiple bonds catalyzed by ytterbium-imine complexes. Tetrahedron Lett 42 6357-6360... 

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