The stereochemistry of 2-alkoxy-4-methyl-1,3,2-dioxaphosphorinans

Abstract

The stereochemistry of a series of 2-alkoxy-4-methyl-1,3,2-dioxaphosphorinans has been investigated by n.m.r. and dipole-moment studies. For a given alkoxy-group (MeO, EtO, or PrⁱO), the more-stable member of the isomeric pair adopts a chair conformation, having the trans-configuration, with equatorial methyl and axial alkoxy-group. The less-stable isomers, having the cis-configuration, adopt rapidly flipping chair conformations. Configurational stability is solvent dependent.