A regioselective entry to 13-substituted 8-oxoprotoberberines. Total synthesis of (.+-.)-corydaline

C Saa, E Guitian, L Castedo, R Suau…

Index: Saa, Carlos; Guitian, Enrique; Castedo, Luis; Suau, Rafael; Saa, Jose Manuel Journal of Organic Chemistry, 1986 , vol. 51, # 14 p. 2781 - 2784

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Citation Number: 23

Abstract

5 the colorless crystalline cycloadduct 4a in 10% and 40%, respectively. The most characteristic features of the latter cycloadduct (MS, m/e (relative intensity) 383 (100)) were its IR spectrum (~ c-0~ 1675 cm-*) and lH NMR spectrum which showed a high field methoxy group at 3.17 ppm. These significant spectroscopic data immediately allowed us to assign structure 4a to this adduct, which had been synthesized by a photochemical route." ...