Nitrogen heterocycles by palladium-catalysed oxidative cyclization-alkoxycarbonylation of acetylenic ureas
作者:Alessia Bacchi、Gian Paolo Chiusoli、Mirco Costa、Cristian Sani、Bartolo Gabriele、Giuseppe Salerno
DOI:10.1016/s0022-328x(97)00459-2
日期:1998.7
Acetylenic ureas readily undergo oxidative cyclization-alkoxycarbonylation reactions in the presence of PdI2 (or Pd/C)-KI as catalyst in methanol under mild conditions (65°C and 24 bar of a 3:1 mixture of CO and air). Cyclization occurs by trans-attack of oxygen or cis-attack of nitrogen functions on the triple bond, followed by stereospecific carbonylation, resulting in E or Z-stereochemistry, respectively
在甲醇中,在温和的条件下(65°C和24 bar的CO和空气的3:1混合物),在甲醇中存在PdI 2(或Pd / C)-KI作为催化剂时,乙炔脲容易发生氧化环化-烷氧基羰基化反应。通过三键上的氧反式攻击或氮功能的顺式攻击发生环化反应,然后进行立体有择的羰基化反应,分别导致E或Z立体化学反应。在二炔脲的情况下,发生稠环形成。该三键还可以通过顺式攻击与一氧化碳和甲醇立体定向反应形成马来酸基团,从而导致Z-立体化学。