B. Alcaide et al., STEREOSELECTIVE SYNTHESIS OF VINYL ETHERS BY THE REACTION OF N-(ARYLIDENE(OR ALKYLIDENE)AMINO)-2-AZETIDINONES WITH OZONE, Journal of organic chemistry, 60(19), 1995, pp. 6012-6016
Ozonolysis of N-(arylidene(or alkylidene)amino)-2-azetidinones followe
d by NaBH4 workup yields enol ethers in good yields with high levels o
f stereoselectivity. Di- and trisubstituted olefin derivatives are ava
ilable through this procedure. Chiral 2-azetidinones lead to enol ethe
rs with a chiral moiety without racemization. The reaction is thought
to occur through a novel B-type fragmentation of the 2-azetidinone rin
g. This process is closely related to the well-known N-nitrosoamide to
ester rearrangement and the decarboxylation of oxetan-2-ones.