Structure of Colchicine

IN view of the remarkable physiological properties of colchicine its chemical nature is of some interest. Until recently, the structure (I) proposed by Windaus1has been generally accepted, although the stability of colchicine did not suggest a 9-amino-9: 10-di-hydrophenanthrene system, and although the salicylaldehyde enol structure of ring C appeared fantastic. Cohen, Cook and Roe2have now provided evidence that ring B must be 7-membered, but the exact location of the acetamido group remains uncertain; the isolation by Windaus of 4-methoxyphthalimide from the oxidation product of acetylcolchinol methyl ether suggested that the group was adjacent to ring C, but Lettré and Fernholz3have found that only β-anisylethylamine derivatives act as mitosis poisons.