| abstract |
The invention provides compounds having the general formula I (See Formula) wherein X is O or S; R1 is C, N, O or S; R1a is CH, CH2, N or NH; R2 is a bond, CH or CH2 m is 1, 2 or 3; n is 1 or 2; when n is 2 or m is 2 or 3, the ring containing R1 may be fused with a benzene ring; each represents a single or double bond with the condition that a double bond extends from the R3? CEC-carbon atom and that no ring carbon atom has two double bonds; and R3, R4 and R5 represent a wide variety of substituents. |