Synthesis and chiroptical properties of pseudocolchicine and neocolchicine, novel unnatural regioisomers of colchicine
作者:Marino Cavazza、Maurizio Zandomeneghi、Francesco Pietra
DOI:10.1039/b109075p
日期:2002.2.6
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.
秋水仙碱 1 的两种新型半异构体,假秋水仙碱((Ra,7S)-N-(1,2,3,11-四甲氧基-10-氧代-5,6,7、((Ra,7S)-N-(1,2,3,11-四甲氧基-10-氧代-5,6,7,11-四氢苯并[a]庚烯-7-基)乙酰胺 11)和新朱古力碱((Ra,7S)-N-(1,2,3,10-四甲氧基-11-氧代-5,6,7,11-四氢苯并[a]庚烯-7-基)乙酰胺 13)、从 10-hydroxyneocolchicide 15 中得到,方法是先用 CH2N2 处理,然后进行 HPLC 分离;或者先用甲苯酰氯处理,然后用 TLC 分离得到的甲苯酸盐 16 和 17,并用 Ti(OMe)4 对其进行特异性甲氧基化。通过观察 11 和 13 以及秋水仙碱 1 和异秋水仙碱 6 类似的紫外光谱和 CD 光谱,我们对秋水仙碱类化合物的电子光谱行为有了更深入的了解。