| abstract |
A new process is provided for the preparation of 5-[(2H-pyrrol-2-ylidene)methyl]-2,2'-bi-1H-pyrrole derivatives of formula (I) wherein R1 represents hydrogen, phenyl, C1-C20 alkyl or C2-C20 alkenyl, wherein the alkyl and alkenyl groups may be unsubstituted or substituted by 1 to 3 substituents chosen independently from halogen, C1-C6 alkoxy, hydroxy, aryl and aryloxy; R2 represents hydrogen, C1-C6 alkyl, cyano, carboxy or (C1-C6 alkoxy)carbonyl; R3 represents halogen, hydroxy or C1-C11 alkoxy unsubstituted or substituted by phenyl; R4 represents hydrogen, C1-C6 alkyl or phenyl; each of R5 and R6 independently represents hydrogen, C2-C20 alkanoyl, C3-C20 alkenoyl, phenyl, C1-C20 alkyl or C2-C20 alkenyl; or two of R4, R5 and R6 taken together form a C4-C12 polymethylene chain, which can be unsubstituted or substituted by a C1-C12 alkyl, by a C2-C12 alkenyl or by a C1-C12 alkylidene group; and the pharmaceutically acceptable salts thereof. |