Synthetic studies of the antitumor antibiotic streptonigrin. II. Synthesis of the C-D ring portion of streptonigrin
作者:T. K. Liao、Philip J. Wittek、C. C. Cheng
DOI:10.1002/jhet.5570130627
日期:1976.12
base-catalyzed condensation with ethyl acetate yielded 3-(2-benzyloxy-3,4-din]etlK>xy)benzoyl-2-butanonc (6). Animation of the latter and subsequent base-catalyzed cyclization with ethyl cyanoacetate gave 4-(2-benzyloxy-3,4-dimethoxy)phenyl-5,6-dimethyl-2-oxo-1,2-dihydropyridine (8). Removal of the 2-oxo group of 8 through chlorination and dechlorination and stepwise conversion of the 5-cyano and 2-methyl
没食子苯乙酮的部分甲酰基(4),然后苄基化和与乙酸乙酯的碱催化缩合,产生3-(2-苄氧基-3,4-二etetK> xy)苯甲酰基-2-丁烷醛(6)。后者的动画化以及随后用氰基乙酸乙酯的碱催化环化反应,得到4-(2-苄氧基-3,4-二甲氧基)苯基-5,6-二甲基-2-氧代-1,2-二氢吡啶(8)。通过氯化和脱氯脱除8的2-氧代基团,并将5-氰基和2-甲基分别逐步转化为5-氨基和2-羧酸基团,并在适当的阶段引入和除去保护基团产生抗肿瘤抗生素链霉菌素的CD环部分。