A number of 5-oxo-2,5-dihydroisoxazoles, substituted with nitrogen heterocycles at N-2, have been subjected to flash vacuum pyrolysis. Annelated imidazoles are obtained in excellent yields, and are presumed to arise by intramolecular cyclisation of an imino carbene intermediate. The heterocycles annelated in this manner include isoquinoline, quinoline, benzothiazole, quinazoline, phenanthridine, pyrimidine
已经对许多在N-2处被氮杂环取代的5-oxo-2,5-dihydroisoxazoles进行了快速真空热解。退火的
咪唑以极高的产率获得,并且推测是由于亚
氨基卡宾中间体的分子内环化而产生的。以这种方式退火的杂环包括
异喹啉,
喹啉,
苯并噻唑,
喹唑啉,
菲啶,
嘧啶和
吡啶。