Methanolysis of 4-Methyl-2,6,7-trioxa-1-phospha-bicyclo[2.2.2]octane 1-Oxide and 1-Sulfide: Mechanistic and Stereochemical Considerations

Abstract

Methanolysis of 4-methyl-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane 1-oxide and 4-methyl-2,6,7- trioxa-1-phosphabicyclo[2.2.2]octane 1-sulfide have been studied by ³¹P n.m.r. spectroscopy. The trans-2-methoxy-5-methyl-1,3,2-dioxaphosphorinane-r-5-methanol 2-oxide and trans-2-methoxy-5-methyl-1,3,2-dioxaphosphorinane-r-5-methanol 2-sulfide are the initially formed products, respectively, but with time a product mixture comprising the trans- and cis -isomers and the acyclic dimethyl phosphate is formed. Methanolysis of the isolated trans-isomer, and of the isolated acyclic dimethyl phosphate under the same reaction conditions, suggests that the cis -isomer results from a recyclization reaction, rather than from the alternative ring opening of the bicyclic compound.