Abstract A two-step synthesis of 4-methylcolchicine (13), starting from colchicine (2), has been developed (Scheme 5). In three steps, 4-ethylcolchicine (28) is also accessible from 2 (Scheme 8). Colchicine (2) and its derivatives 13 and 28 have been transformed into the benzo [a] heptalene derivatives 9, 18, and 34, respectively, by Hofmann degradation of the corresponding deacetylcolchiceine 3, 19, and 29, respectively, followed by methylation of ...
![1,2,3,10-tetramethoxy-7H-benzo[a]heptalen-9-one结构式](https://image.chemsrc.com/caspic/376/76265-61-7.png)