The structures of three gamma-lactone derivatives, methyl oxa-10-oxobi
cyclo[6.3.0]undec-4-ene-9-carboxylate, C12H16O4, methyl oxa-10-oxobicy
clo[6.3.0]undec-2-ene-9-carboxylate, C12H16O4, and methyl 9-oxa-10-oxo
bicyclo[6.3.0]undecane-11-carboxylate C12H18O4, have been solved in or
der to determine the relative configuration of their three asymmetric
stereocentres.