Abstract1‐O‐Acetyl‐1‐O‐demethylcolchicine, and acylated 1‐O,2‐O‐didemethylthiocolchicines, in contrast to 2‐O‐acetyl‐, 2‐O,3‐O‐diacetyl‐ and 3‐O‐acetyl analogs, showed after standing in CHCl3solution significant changes in optical rotation, a duplication of1H‐NMR signals, and the formation of new isomers on TLC. Solid‐state X‐ray diffraction ofO‐acetylated colchinoids and thio analogs, showed out of planar arrangements of the aromatic substituents, but the analysis could not help to explain the structures of