A new access to phosphaindolizines by [3+2] cycloaddition of azomethine ylides onto phosphaalkynes
作者:Uwe Bergsträßer、Andreas Hoffmann、Manfred Regitz
DOI:10.1016/s0040-4039(00)91856-2
日期:1992.2
Azomethine ylides such as 1 and 4 in which the nitrogen atom is incorporated in a six-membered heterocyclic ring undergo regiospecific [3+2] cycloadditions with the phosphaalkynes 2a and b at 130–140 °C to furnish the phosphaindolizines 3 and 5a–c after elimination of ethyl formate or hydrogen cyanide, respectively. In contrast, dipoles of the type 6 react unspecifically with the phosphaalkyne 2a to
氮杂亚胺基化物(如1和4)中的氮原子并入六元杂环中,在130–140°C下与磷炔烃2a和b发生区域特异性的[3 + 2]环加成反应,从而提供磷吲哚并嗪3和5a–c分别去除甲酸乙酯或氰化氢后。相反,类型6的偶极与磷炔2a发生非特异性反应,生成区域异构体7和8。