Synthesis of novel 1,3,4-oxadiazin-5(6H)-ones and 2-hydroxymethyl-1,3,4-oxadiazoles

Reactions of (x-hydroxyacid hydrazides (benzilic, R- and S-mandelic) and triethyl orthoesters (orthoformate, orthoacetate, orthopropionate, orthobenzoate) in glacial acetic acid resulted in two groups of heterocyclic compounds, derivatives of 6-phenyl- 1,3,4-oxadiazin-5-(6H)-one and 2-hydroxyinethyl-1,3,4-oxadiazole. Their structures were confirmed by typical spectroscopic methods and X-Ray analysis. Spectral characteristic of the compounds and attempts to elucidate the mechanism are discussed.