Olivanic acid analogues. Part 11. Ozonolysis of α-ethylideneazetidinones: ozonide fragmentation to α-amino acid-N-carboxyanhydrides
Abstract
Ozonolysis of (E)-7-ethylidene[3-oxa-1-azabicyclo[4.2.0]octane-2-spirocyclohexan]-8-one failed to provide the α-oxoazetidinone 2, but afforded an α-amino acid-N-carboxyanhydride [3,8-dioxa-1-azabicyclo[4.3.0]nonane-2-spirocyclohexane]-7,9-dione 5. [3-Oxa-1-azabicyclo[4.2.0]octane-2-spirocyclohexane]-7,8-dione 2 was instead obtained from the trans-ketone 9 by a sequence involving Baeyer–Villiger oxidation of the azido ketone 10.