methylenomycin A

(1R)-2,3-Dimethyl-2α,3α-epoxy-4-oxo-5-methylenecyclopentane-1β-carboxylic acid

(+)-1α,5α-Dimethyl-3-methylene-4-oxo-6-oxabicyclo[3.1.0]hexane-2α-carboxylic acid