Preparation of New Nitrogen-Bridged Heterocycles. 44. Thermolysis of 12bH-1,4-Thiazepino[5,4-a]isoquinoline Derivatives.
作者:Akikazu KAKEHI、Suketaka ITO、Satoshi NISHIZAWA
DOI:10.1248/cpb.46.934
日期:——
Thermolysis of trialkyl 4-alkylthio-12bH-1, 4-thiazepino[5, 4-a]isoquinoline-1, 2, 5-tricarboxylates in refluxing xylene did not afford the usually expected desulfurized products such as benzoquinolizine derivatives (5), but formed trialkyl 2-(1-isoquinolinyl)-4-alkylthio-2, 3-dihydrothiophene-2, 3, 5-tricarboxylates (4) in low to moderate yields. A similar treatment of the title compounds in the presence of a base such as 1, 8-diazabicyclo[5.4.0]undec-7-ene gave ring contraction and fragmentation products, trialkyl pyrrolo[2, 1-a]isoquinoline-1, 2, 3-tricarboxylates in moderate yields. 1, 5-Sigmatropic shift of 7-thianorcardiene intermediates is involved in the formation of 2-(1-quinolinyl)-2, 3-dihydrothiophene derivatives.
在回流二甲苯中,4-烷硫基-12bH-1,4-噻嗪并[5,4-a]异喹啉-1,2,5-三羧酸三烷基酯热分解并没有得到通常预期的脱硫产物,如苯喹嗪衍生物(5),而是以低至中等产率形成了 2-(1-异喹啉基)-4-烷硫基-2,3-二氢噻吩-2,3,5-三羧酸三烷基酯(4)。在 1,8-二氮杂双环[5.4.0]十一碳-7-烯等碱存在下对标题化合物进行类似处理,可得到缩环和碎裂产物--三烷基吡咯并[2,1-a]异喹啉-1,2,3-三羧酸盐,收率中等。7-噻吩-2,3-二氢噻吩衍生物的形成涉及 7-噻吩-2,3-二氢噻吩中间体的 1,5-偏移。