Alkyl, aryl, heteroaryl and acyl radicals have been cyclised onto the 2-position of 3H-quinazolin-4-one. The side chains containing the radical precursors were attached to the nitrogen atom in the 3-position. The cyclisations take place by aromatic homolytic substitution hence retain the aromaticity of the 3H-quinazolin-4-one ring. The highest yields were obtained using hexamethylditin to facilitate cyclisation rather than reduction without cyclisation. The alkaloids deoxyvasicinone 2, mackinazolinone 3, tryptanthrin 4, luotonin A 5 and rutaecarpine 8 were synthesised by radical cyclisation onto 3H-quinazolin-4-one.
烷基、芳基、杂芳基和酰基自由基已环化连接到3H-
喹唑啉-4-酮的2-位。含有自由基前体的侧链被连接到3-位的氮原子上。环化反应通过芳香均裂取代进行,因此保留了3H-
喹唑啉-4-酮环的芳香性。使用
六甲基二锡促进环化而不是直接还原而未发生环化,最高产率得以实现。
生物碱去氧vasicinone 2、mackinazolinone 3、
色胺酮4、luotonin A 5和rutaecarpine 8通过自由基环化反应合成于3H-
喹唑啉-4-酮。