关键词: 生物碱, 红外分光光度法, 质谱法, 环化, 质子磁共振谱法, 硝基小檗因, 酰烯胺

Six berbine derivatives 2f~2k with nitro group in ring D have been synthesized via photocyclization 2-methoxy-nitro-benzoyl chlorides reacted with 1-methyl-6,7-dimethoxy (or 6-methoxy-7-benzyloxy)-3,4- dihydro-isoquinolines to give 1-methylene-6,7-dimethoxy (or 6-methoxy- 7-benzyloxy)-N-(2'-methoxy-nitro-benzoyl)-1,2,3,4-tetrahydro- isoquinolines (3) along with unexpected by-products whose structures were identified as 1-methyl-1-(2'-methoxy-benzoyl)-6,7-dimethoxy (or 6-methoxy-7-benzyloxy)-1,2,3,4-tetrahydro-isoquinolines (5). Irradiation of compounds 3 in methanol gave 2,3-dimethoxy (or 2- benzyloxy-3-methoxy) 8-oxo-13,13a-didehydro-berbines (4) with nitro group in ring D and a small amount of corresponding 5. Compounds 4 were treated with POCl3 followed by NaBH4 to afford the berbine derivatives 2f~2k.

Key words: ALKALOID, INFRARED SPECTROPHOTOMETRY, MASS SPECTROGRAPHY, CYCLIZATION, PROTON MAGNETIC RESONANCE SPECTROMETRY