The asymmetric synthesis of α-substituted α-methyl and α-phenyl phosphonic acids: Design, carbanion geometry, reactivity and preparative aspects of chiral alkyl bicyclic phosphonamides

Article abstract of DOI:10.1016/0040-4020(96)00829-0

The design, preparation, structural and spectroscopic analyses of topologically unique and enantiomerically pure alkyl phosphonamides are described. In the case of α-ethyl and α-benzyl phosphonamides, the geometry of both the secondary and tertiary carbanions was determined to be planar through deprotonation/deuteration/alkylation experiments. Stereoselective alkylations of such systems proceeded in good yields and with high diastereoselectivities. The resulting α,α-alkylated phosphonamides were hydrolyzed to give the corresponding α,α-alkyl phosphonic acids with high degrees of enantiomeric purity.