A Versatile New Method for Synthesis of Isoquinolines; 6,8-Dihydroxyisoquinoline Derivatives from 6-Methyl-1,3-oxazin-4-ones
摘要:
A versatile method for synthesis of isoquinolone derivatives (4a-h) from 2-substituted 6-methyl-4H-1,3-oxazin-4-ones (1a-h) is described. Transformation of 1a-h with diethyl acetonedicarboxylate (2) in the presence of potassium tert-butoxide afforded 6-substituted 3-acetyl-5-ethoxycarbonyl-4-ethoxycarbonylmethylene-2-pyridones (3a-h) in excellent yields. Dieckmann-type cyclization of 3a-h with sodium ethoxide in ethanol produced the corresponding isoquinolone derivatives (4a-h) in good yields, respectively.
描述了通过三种互补方法制备各种2,6-二取代的4 H -1,3-恶嗪-4-酮3的简便方法。在催化量的乙酸存在下用双烯酮1处理支链脂族亚氨酸酯2c,d,得到2-取代的6-甲基-1,3-恶嗪-4-酮3c,d,而未支链的亚氨酸酯2b,e得到恶嗪3b,e和嘧啶4b,e(方法A)。酰基麦德鲁姆酸5与亚氨酸酯2的反应得到2,6-二取代的恶嗪3,尽管烷基亚胺基丁酸酯与乙酰基麦德鲁姆的酸产生3和5-乙酰基-1,3-恶嗪-4,6-二酮8(方法B)。酰基乙酰基羧酰胺13的烷基脱水 用酸,例如70%高氯酸或氟磺酸,得到1,3-恶嗪3(方法C)。