| abstract |
Novel compounds having various biological activities useful as drugs and animal drugs. Compounds represented by general formula (I) and salts or metal complexes thereof, wherein R1 represents COOR?4, CONR5R6, CO-R7¿-OR or CH¿2?OR?8; R2¿ represents hydrogen, alkyl, aralkyl, heteroaryl, heteroaryl-alkyl, COR?13, COOR14¿ or CONR?15R16; R3¿ represents oxygen or OR3'; and the broken line (- - -) represents the presence of a double bond when R3 is oxygen, or the absence of a double bond when R?3 is OR3'¿. |