Chemical Transformation of Protoberberines. XIV. Acid-Catalyzed Cleavage of 8-Alkyl-8, 14-cycloberbines. A Simple Method for the Preparation of N-Unsubstituted Spirobenzylisoquinolines

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...

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Veröffentlicht in:Chemical & pharmaceutical bulletin 1987/08/25, Vol.35(8), pp.3155-3165
Hauptverfasser: HANAOKA, MIYOJI, KIM, SIN KYU, SAKURAI, SHUN-ICHIRO, SATO, YUKO, MUKAI, CHISATO
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Sprache:eng
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Zusammenfassung: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).
ISSN:0009-2363
1347-5223
DOI:10.1248/cpb.35.3155