Patent ID: 7384906

Claim:
A compound of formula I wherein R 1 and R 3 are independently hydrogen, methyl, or ethyl; R 2 is hydrogen, methyl, ethyl, methylene, or ethylidene; R 4 is C 1 to C 4 alkyl; or R 4 is vinyl or a linear, branched or cyclic C 3 to C 4 alkenyl; X is carbonyl or a divalent radical —(CMe 2 )-; Y is oxygen or a divalent radical —(CH 2 )—; the bond between C-2 and R 2 is a single bond, and the bond between C-2 and C-3 together with the dotted line represents a double bond; or the bond between C-2 and C-3 is a single bond, and the bond between C-2 and R 2 together with the dotted line represents a double bond; or the bond between C-2 and R 2 is a single bond and the bond between C-2 and C-3 is a single bond.