Hydrophosphination intermolecular

Organolanthanide complexes are known to be highly active catalysts for a variety of organic transformations, which can be either intramolecular or intermolecular in character. Successful intramolecular transformations include hydroelementation processes, which is the addition of a H-E (E = N, O, P, Si, S, H) bond across unsaturated C-C bonds, such as hydroamination, hydroalkoxylation, and hydrophosphination. Intermolecular transformations include a series of asymmetric syntheses, the amidation of aldehydes with amines, Tishchenko reaction, addition of amines to nitriles, aUcyne dimerization, and guanylation of terminal aUcynes, amines, and phosphines with carbodiimides. 

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 STYRENE CATALYZED BY CHARGE-NEUTRAL HETEROLEPTIC COMPLEXES OF LARGE ALKALINE EARTHS... 

Scheme 28.10 Intermolecular hydrophosphination of styrene catalyzed by heteroleptic Ae complexes [27].

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

In 2007, Hill and coworkers reported the intermolecular hydrophosphination of activated alkenes with diphenylphosphine catalyzed by [ (ArNCMe)2CH Ca N(SiMe3)2 (THF)] [106]. Reactions were conducted in benzene solution and... 

Crimmin MR, Barrett AGM, Hill MS, Hitchcock PB, Procopiou PA (2007) Calcium-catalyzed intermolecular hydrophosphination. Organometallics 26 2953-2956... 

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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