63569-08-4 Butanoic acid, 2-methyl-, (3S,3aR,4S,4aR,7aR,8R,9aR)-2,3,3a,4,4a,5,7a,8,9,9a-decahydro-3,4a,8-trimethyl-2,5-dioxoazuleno(6,5-b)furan-4-yl ester Butanoic acid, 2-methyl-, 2,3,3a,4,4a,5,7a,8,9,9a-decahydro-3,4a,8-trimethyl-2,5-dioxoazuleno(6,5-b)furan-4-yl ester, stereoisomer Microhelenin B