Dialkylphosphinates synthesis

Synthesis of (Silylamino)phosphines. In a typical preparation, addition of one molar equivalent of PCI3 to a stirred solution of LiN(SiMe3)2 in ether at -78°C followed by one or two equivalents of an alkyl Grignard or lithium reagent at 0°C gives the corresponding mono- or dialkylphosphine. This proce-... 

Alkylphosphines. The reagent LiPH2 is prepared from red P, Li, and r-BuOH in liquid ammonia, and used immediately. Thus the addition of an alkyl halide to the solution furnishes the primary alkylphosphine. On the other hand, a one-pot synthesis of dialkylphosphines needs NaNH2 to promote the second alkylation. 

Several communications, summarized in Scheme 14, have described the synthesis of many amino-substituted dialkylphosphinic acids and phosphonic acids, and also many similarly substituted hydrogenphosphinic acids. Alkylation of the phosphinates (272) (R = H or Me, = Et, R = H) yields the corresponding (273) which, in a single step, are convertible into the useful intermediates (274). With 1,2-unsaturated nitriles, for example, the (3-aminopropyl)phosphinic acids... 

The novel synthesis of unsymmetrical dialkylphosphinic acids (573) under mild conditions has been performed by Lecouvey and co-workers.This synthesis started from the hypophosphoric acid (570) which reacted with triethyl orthoformate to give the //-phosphinate (571). The letter underwent base-promoted alkylation to give (572). For the formation of the second P-C bond in the phosphinate (573), a one-pot procedure involving reaction of (572) has been applied (Scheme 139). This methodology was extended to the synthesis of dialkylphosphinic acids with amino functionality. 

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