New Cyclization Mode of [N-(Diarylmethyleneamino)carbonimidoyl]ketenes: Synthesis of 9H-Pyrazolo[3,2-b][1,3]benzoxazines
作者:Natalia A. Lisowskaya、Mateo Alajarin、Pilar Sanchez-Andrada
DOI:10.1002/ejoc.200500768
日期:2006.3
-carboxylates 2a and 2b gave the novel methyl 3-acyl-9-hydroxy-9-phenyl-9H-pyrazolo[3,2-b][1,3]benzoxazine-2-carboxylates 4a and 4b, the structures of which were determined by X-ray crystallography. The proposed mechanism for this conversion, involving the [N-(o-bromo-α-phenylbenzylideneamino)carbonimidoyl]ketenes 5 and the mesomeric betaines 6 as intermediates, has been investigated by ab initio and
3-酰基-1-[o-溴苯基(苯基)亚甲基氨基]-4,5-二氧-4,5-二氢-1H-吡咯-2-羧酸甲酯2a和2b的热脱羰得到新的3-酰基甲酯-9-羟基-9-苯基-9H-吡唑并[3,2-b][1,3]苯并恶嗪-2-羧酸酯4a和4b,其结构由X射线晶体学确定。已通过 ab initio 和 DFT 计算研究了这种转化的拟议机制,涉及 [N-(o-溴-α-苯基亚苄基氨基)carbonimidoyl] 烯酮 5 和内消旋甜菜碱 6 作为中间体。(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)