Thiocolchicine (II) was prepared from colchicine (I) by treatment with sodium methylthiolate. Then, hydrolysis of acetamide group with methanolic HCl afforded deacetyl thiocolchicine (III). Subsequent acylation with p-nitrobenzoyl chloride (IV) in the presence of pyridine provided amide (V), which was demethylated with excess BBr3 to give the corresponding triphenol (VI). Finally, esterification with acetyl chloride in the presence of pyridine and 4-(dimethylamino)pyridine furnished the target triacetate.
Thiocolchicine (II) was prepared from colchicine (I) by treatment with sodium methylthiolate. Then, hydrolysis of acetamide group with methanolic HCl afforded deacetyl thiocolchicine (III). Subsequent acylation with p-nitrobenzoyl chloride (IV) in the presence of pyridine provided amide (V), which was demethylated with excess BBr3 to give the corresponding triphenol.