Colchicine and Related Bases

Demethylation of colchicine with concentrated sulphuric acid at 80-90°C gives 2-demethylcolchicine, and under the same conditions 1- and 3-0-demethylcolchicine give respectively the 1,2-0-demethyl- 

Following a route previously developed for the synthesis of deacetamidocolchicine, (+)-colchicine has been synthesised from (136 R = R = OMe), which was hydrolysed by acid to (136 RR = 0) and this was cyclised by boron trifluoride etherate to the acid (137). Ring-expansion of the methyl ester of (137) with trifluoroacetic acid gave a mixture of (138) and the isomeric ag-unsaturated ester, both of which, on oxidation, gave the tropolone (139), hydrolysis and decarboxylation of which gave deacetairaido-isocolchicine. Hydrolysis of (139) and treatment with diphenyl- 

Slavik and L. Slavikova, Coll. Czech. Chern. Commun., 1981, 1534. 

Russo and E.G. Gros, J. Labelled Compds.Radiopharm.. I98I, II85. 

Tsunashima, H. Shinoki, 0. Hoshino and B. Umezawa, Heterocycles, 1982, (Special Issue), 293- 

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