Derivatives of orthoacids. I. Bicyclic orthoesters

Abstract

Ethyl orthoformate reacts with butane-1,2,4-triol, pentane-1,2,5-triol, and pentane-1,3,5-triol to form 2,7,8-trioxabicyclo[3,2,1]octane, 2,8,9-trioxabicyclo[4,2,1]nonane, and 2,8,9-trioxabicyclo[3,3,1]nonane respectively. Attempts to prepare the analogous bicyclic orthoesters from glycerol and 2-hydroxymethyl-butane-1,4-diol led to monocyclic derivatives and to polymers. The ease of formation and stability of these bicyclic compounds are contrasted with those of 4-methyl-2,6,7-trioxabicyclo[2,2,2]octane and the results are discussed in relation to the stereochemistry of the transition state in ester and amide hydrolysis.