Chemical transformation of protoberberines. XIV. Acid-catalyzed cleavage of 8-alkyl-8,14-cycloberbines. A simple method for the preparation of N-unsubstituted spirobenzylisoquinolines.
作者:MIYOJI HANAOKA、SIN KYU KIM、SHUN-ICHIRO SAKURAI、YUKO SATO、CHISATO MUKAI
DOI:10.1248/cpb.35.3155
日期:——
On treatment with an acid, 8-alkyl-8, 14-cycloberbines (9) afforded the N-unsubstituted spirobenzylisoquinolines (10, 11, and 12) through regioselective C8-N bond cleavage in contrast to the 8-unsubstituted 8, 14-cycloberbine (9d), which gave the benzindenoazepine (19, R = H) through regioselective C14-N bond cleavage. Reduction of 9 with NaBH4 or LiAlH (OBut) 3 yielded stereoselectively the alcohol (20 or 21, respectively) as the main product. Acidic treatment of the isomeric alcohols (20 and 21) effected regioselective C8-N bond cleavage, resulting in the N-unsubstituted spirobenzylisoquinolines (22-26).
在用酸处理时,8-烷基-8,14-环小檗碱(9)通过区域选择性 C8-N 键裂解得到 N-未取代的螺苄基异喹啉(10、11 和 12),而 8-未取代的 8,14-环小檗碱(9d)则通过区域选择性 C14-N 键裂解得到苯并茚并氮杂卓(19,R = H)。用 NaBH4 或 LiAlH (OBut) 3 还原 9,可以立体选择性地得到作为主要产物的醇(分别为 20 或 21)。酸性处理异构醇(20 和 21)可实现区域选择性 C8-N 键裂解,从而得到 N-未取代的螺苄基异喹啉(22-26)。