Investigation of conformational equilibrium in a series of some 1,3-dioxa-2-phosphorinanes

Abstract

1. The IR spectra of certain 1,3-dioxa-2-phosphorinanes were studied under conditions of various polarities of the medium and temperatures, and it was shown that 2,4-dimethy1-2-thiono- and 2-chloro-2-thiono-1,3-dioxa-2-phosphorinanes are characterized by stabilization of one conformational form, while for 2-methyl-2-thiono-1,3-dioxa-2-phosphorinane a dynamic equilibrium of two conformers is realized with an appreciable dependence of their amounts on the dielectric permeability of the medium. 2. An equilibrium of three conformers was detected for 2-chloro-4-methyl-2-thiono-1,3-dioxa-2-phosphorinane. It was hypothesized that, together with the "chair" conformation of the ring with axial and equatorial positions of the P=Sbond, the conformer with an equatorial arrangement of the P=S bond and a "boat" form of the ring participates in the equilibrium. © 1973 Consultants Bureau.