190836-00-1Relevant articles and documents
Chemoselective Reduction of the P=O Bond in the Presence of P–O and P–N Bonds in Phosphonate and Phosphinate Derivatives
Sowa, Sylwia,Pietrusiewicz, K. Micha?
, p. 923 - 938 (2019/01/22)
Chemoselective reduction of the strong P=O bond in the presence of weaker P–O (ester) and P–N (amide) bonds in phosphonic acid derivatives has constituted an unresolved problem in organophosphorus chemistry for years. This long-standing problem is now solved for biologically relevant α-hydroxy and α-amino phosphonic as well as phosphinic acids esters and amides. The reduction of the P=O bond without concomitant scission of the ester and amide bonds is affected by use of BH3, a mild reducing agent, which affords the corresponding borane protected PIII phosphonite and phosphinite derivatives in one step. A mechanistic rationale is proposed for the role played by neighboring OH and NHR groups in facilitating the reduction, and for the observed chemo- and stereoselectivity. The reduction methodology described opens previously unavailable synthetic options in chemistry of α-functionalized phosphonic and phosphinic acids by offering a unique possibility for direct modifications of oxidation level of the P-center in these compounds.
