Olefins, activated, hydrophosphination

Kovacik, I., Wicht, D.K., Grewal, N.S., Glueck, D.S., Incarvito, C.D., Guzei, I.A., and Rheingold, A.L., Pt(Me-Duphos)-catalyzed asymmetric hydrophosphination of activated olefins enantioselective synthesis of chiral phosphines,... 

The mechanistic study on the hydrophosphination of activated olefins, in conjunction with rapid inversion of the configuration at the phosphorus center, was elaborated to develop asymmetric hydrophosphination catalyzed by a chiral phosphine platinum complex although the % ee is not excitingly high yet (Scheme 9) [15]. 

A different approach must be used for the photochemical hydrophosphination of electron-poor olefins, and this involves a PET reaction. Silyl phosphites (e.g., 30) were used as electron donors, whereas conjugated ketones have the double role of electron acceptors and absorbing species. Thus, the irradiation of a mixture containing 2-cydohexenone and 30 generated an ion pair. The phosphoniumyl radical cations decomposed to give trimethylsilyl cations (which in turn were trapped by the enone radical anion) and phosphonyl radicals. A radical-radical combination afforded the 4-phosphonylated ketones in yields ranging from 78% to 92% (Scheme 3.20) [49]. This reaction was exploited for the preparation of substituted phosphonates, which serve as key intermediates in the synthesis of a class of biologically active compounds. 

The binuclear palladium complex [(tBu2PH)PdPtBu2]2 with oxygen gave a very efficient catalyst for the hydrogenation of a,/3-unsaturated carbonyls. 0 Glueck and co-workers have undertaken studies on aspects of platinum-catalyzed hydrophosphinations of activated olefins.71,72... 

The Duphos ligand (157) has been used to prepare organometallic complexes of palladium.385 Rhodium complexes of ligands (156), (157), or (159) are efficient catalysts for enantioselective hydrogenations337-341,343,345,386-388 and furthermore, in the case of platinum complexes with (157), as catalysts for the asymmetric hydrophosphination of activated olefins.71... 

Scriban C, Kovacik I, Glueck DS (2005) A protic additive suppresses formation of byproducts in platinum-catalyzed hydrophosphination of activated olefins. Evidence for P-C and C-C bond formation by Michael addition. Organometallics 24 4871-4874... 

Yuan M, Zhang NA, Pullarkat S, Li Y, Liu F, Pham P-T, Leung P-H (2010) Asymmetric synthesis of functionalized 1,3-diphosphines via chiral palladium complex promoted hydrophosphination of activated olefins. Inorg Chem 49 989-996... 

Hydroxo-bridged dinuclear complexes, [Pt(P-P)(/u-OH)]2 (where P-P = DIOP, BINAP, NORPHOS, MeDUPHOS, and BPPM) as precursors have been used for the enantioselective Baeyer-Villiger oxidation of ketones (290). The platinum(O) catalyst precursor, Pt(MeDUPHOSXfrans-stylbene), catalyzes the asymmetric hydrophosphination of activated olefins (291). 

Glueck et al. have reported the addition reaction to activated alkenes (Michael acceptors) and have carried out detailed mechanistic studied [121,122]. An important mechanistic study was also carried out for the palladium catalyzed asymmetric phosphination [123, 124]. Hydrophosphination of less activated olefins was achieved for the first time by Ni-catalyzed reaction using phosphite ligands (Scheme 8.44) [125],... 

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