Rh(II)-catalysed carbenoid cyclisations in a stereoselective approach to α-quaternary pipecolic acid derivatives
作者:Mioara Andrei、Christian Römming、Kjell Undheim
DOI:10.1016/j.tetasy.2004.03.018
日期:2004.4
derivatives has been carried out by intramolecular rhodium(II)-carbenoid cyclisation reactions with diazoketones in the geminally disubstituted chiron (R)-2-isopropyl-3,6-dimethoxy-2,5-dihydropyrazine. Both enantiomeric pairs of the pipecolic acid derivatives have been prepared from the same chiron. Exclusive chemoselectivity was seen in the rhodium(II)-carbenoid reactions, which occurred at the adjacent
α-季戊四烯酸衍生物的制备已通过在双取代的双取代的Chiron(R)-2-异丙基-3,6-二甲氧基-2,5-二氢吡嗪中与重氮酮进行分子内铑(II)-类胡萝卜素环化反应来进行。胡椒酸衍生物的两个对映异构体对都由相同的Chiron制备。在铑(II)-类胡萝卜素反应中发现了唯一的化学选择性,该反应发生在相邻的环状氮原子处。受控的酸水解提供了相应的二酮哌嗪或相应的戊基-哌酸二肽。单晶X射线结构分析已用于建立区域化学和相对立体化学。