Patent ID: 7456162

Claim:
A compound represented by the formula: wherein R 1 and R 2 are the same or different and each is hydrogen atom, a hydrocarbon group that may be substituted or a heterocyclic group that may be substituted, or R 1 and R 2 may form, together with the adjacent carbon atom, a 3- to 8-membered homocyclic or heterocyclic ring that may be substituted; is a single bond or a double bond; W is (i) a group represented by the formula: wherein R 4 is (1) an aliphatic hydrocarbon group which is substituted with an aromatic group that may be substituted and, said, may further be substituted or (2) an acyl group containing an aromatic group that may be substituted; R 5 is hydrogen atom, a C 1-6 alkyl group, or an acyl group and, R 3 is a C 6-14 aryl group that may be substituted and ring C is benzene ring that may further be substituted, in addition to the group represented by Wb, or a salt thereof.