Patent ID: 7678748

Claim:
A compound of formula: wherein R and R′ each independently is selected from the group consisting of H, CH 3 , C 2 H 5 , C 3 H 7 , C 4 H 9 , C 5 H 11 , CH(CH 3 )CH 2 CH 2 CH 3 , CH 2 CH(CH 3 )CH 2 CH 3 , CH 2 CH 2 CH(CH 3 )CH 3 , cyclopropyl, cyclobutyl, cyclopentyl, CH═CHCH 2 CH 2 CH 3 , CH 2 CH═CHCH 2 CH 3 , CH 2 CH 2 CH═CHCH 3 , and CH═C(CH 3 )CH 2 CH 3 .