Patent ID: 7399773

Claim:
A compound of Formula (18) or a pharmaceutically acceptable salt thereof wherein R 1 is —XR wherein X is O, S, or Se, or R 1 is wherein R 2 or R 3 is independently alkyl, cycloalkyl, arylalkyl, or aryl or R 2 and R 3 together are —(CH 2 ) 4 —, —(CH 2 ) 5 —, —(CH(R 4 )—CH 2 ) 3 —, —(CH(R 4 )—CH 2 ) 4 —, —(CH(R 4 )—(CH 2 ) 2 —CH(R 4 ))—, —(CH(R 4 )—(CH 2 ) 3 —CH(R 4 ))—, —CH 2 —CH 2 -A-CH 2 —CH 2 —, —CH(R 4 )—CH 2 -A-CH 2 CH 2 —, —CH(R 4 )—CH 2 -A-CH 2 —CH(R 4 )— wherein R 4 is alkyl of from one to four carbon atoms, A is O, S, or N, and R is alkyl, aryl, arylalkyl, or heteroaryl with the proviso that R 1 is not —O— tertiary butyl or —O— methyl.