The methine base (X) derived from berberine chloride via several steps is photocyclized to the two isomeric carbinolamine forms (XI and XII) of 10b-methyl-4b, 10b, 11, 12-tetrahydrochelerythrine. Spectral data and chemical evidences reveal that the positions of the hydroxyl groups are C-6 in XI and C-4b in XII. The cis B/C ring juncture in XI is determined by observation of the nuclear Overhauser effect between 10b-Me and 4b-H. The formation pathways of XI and XII are examined and deduced to be the photoinduced intramolecular alkylation on carbon in the enamine system with olefin.
通过几个步骤从
小檗碱氯化物衍生得到的甲川碱(X),在光照下环化生成两种异构的
甲醇胺形式(XI和XII),即10b-甲基-4b,10b,11,12-四氢
白屈菜红碱。光谱数据和
化学证据揭示,羟基的位置在XI中为C-6,在XII中为C-4b。XI中的顺式B/C环接合点通过观察10b-甲基与4b-氢之间的核奥氏效应确定。XI和XII的形成途径被检查并推断为烯胺体系中烯烃上的光诱导分子内烷基化反应。