| abstract |
Accordingly, the present invention provides a compound of Formula I, or tautomers or isomers thereof, n n n wherein: R1 is a branched chain lower alkyl (C3 to C8), cycloalkyl (C3 to C8), alkyl-substituted alkyl (C4 to C8), bicycloalkyl, 1-adamantyl, polyhaloalkyl, trialkylsilyl, unsubstituted phenyl or substituted phenyl; R2 and R3 are independently unsubstituted or substituted aromatic rings; and R4 is hydrogen, alkyl, alkylthio, alkylthioalkyl, acyloxyalkyl, alkyl, acyl, trialkylsilyl, or cyclized together with R3 and O to form a lactone of the tautomeric form. |