M. Cavazza, M. Zandomeneghi, F. Pietra
Feb 6, 2002
Citations
0
Influential Citations
3
Citations
Journal
Journal of The Chemical Society-perkin Transactions 1
Abstract
Two novel regioisomers of colchicine 1, pseudocolchicine ((Ra,7S)-N-(1,2,3,11-tetramethoxy-10-oxo-5,6,7,10-tetrahydrobenzo[a]heptalen-7-yl)acetamide 11) and neocolchicine ((Ra,7S)-N-(1,2,3,10-tetramethoxy-11-oxo-5,6,7,11-tetrahydrobenzo[a]heptalen-7-yl)acetamide 13), were obtained from 10-hydroxyneocolchicide 15 by either treatment with CH2N2followed by HPLC separation, or treatment with tosyl chloride followed by TLC separation of the resulting tosylates 16 and 17 and their regiospecific methoxylation with Ti(OMe)4. The observation of similar UV and CD spectra for 11 and 13, and for colchicine 1 and isocolchicine 6, allowed us to come to a far reaching rationalisation of the electronic spectral behaviour of colchicinoids.