Thermal decomposition of 2H-(1,2,4)oxadiazolo(2,3-a)pyridine-2-thione and 2H-(1,2,4)oxadiazolo(2,3-b)pyridazine-2-thiones: Generation of aza-heteroaromatic .ALPHA.-isocyanates and their utilization for the synthesis of unsymmetrical disubstituted ureas.
作者:AKIO OHSAWA、HEIHACHIRO ARAI、HIROSHI IGETA
DOI:10.1248/cpb.28.3570
日期:——
Thermal decomposition of 2H-[1, 2, 4] oxadiazolo [2, 3-a] pyridine-2-thione afforded 3-(2-pyridyl)-2H-pyrido [1, 2-a]-1, 3, 5-triazine-2, 4 (3H)-dione and 1, 3-di (2-pyridyl) urea, and similar decomposition of its pyridazine analog afforded 3-(3-pyridazinyl)-2H-pyridazino [1, 6-a]-1, 3, 5-triazine-2, 4 (3H)-dione and 1, 3-di (3-pyridazinyl) urea. Aza-heteroaromatic α-isocyanates, which are intermediates in the decomposition, were utilized for the synthesis of unsymmetrical 1, 3-disubstituted ureas.
2H-[1, 2, 4]噁二唑[2, 3-a]吡啶-2-硫酮的热分解生成了3-(2-吡啶基)-2H-吡啶[1, 2-a]-1, 3, 5-三嗪-2, 4(3H)-二酮和1, 3-二(2-吡啶基)脲,而其吡唑类似物的类似分解则生成了3-(3-吡唑基)-2H-吡唑[1, 6-a]-1, 3, 5-三嗪-2, 4(3H)-二酮和1, 3-二(3-吡唑基)脲。在分解过程中产生的氮杂杂环α-异氰酸酯被用于合成不对称的1, 3-二取代脲。