Sigmatropic Isomerizations in Azaallyl Systems:XXI.Alkanimidoylphosphonates and Their Prototropic and Phosphorotropic Isomers

摘要

Synthetic procedures for alkanimidoylphosphoryl derivatives with alpha-hydrogen atoms in the N-alkyl radical are developed.Data on the effect of substituents at the carbon and phosphorus atoms on the facility of prototropic transitions in the C=N-C triad are summarized.The most facile proton transfer occurs in the N-benzyl derivatives,and the prototropic isomer is the more stable,the stronger the electron-acceptor power of the substituent at the sp~3-carbon atom of the azaallyl triad.The proton transfer in N-(alpha-phenethyl)-trifluoroacetimidoylphosphonates proceeds selectively,which allows preparation of enantiomerically enriched derivatives of alpha-aminotrifluoroethylphosphonic acid.A specific effect of substituents at the phosphorus atom on the prototropism attendant on phosphorylation of imidoyl chlorides is demonstrated.