2-Butenoic acid, 2-methyl-, 2,4,4a,5,6,7,8,9a-octahydro-3,4a,5-trimethyl-2-oxonaphtho(2,3-b)furan-6-yl ester, (4aR-(4aalpha,5alpha,6alpha,6(Z),9abeta))- 74799-14-7