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.