Organocatalyzed route to enantioenriched pipecolic esters: decarboxylation of an aminomalonate hemiester
作者:Thomas Seitz、Jérôme Baudoux、Henri Bekolo、Dominique Cahard、Jean-Christophe Plaquevent、Marie-Claire Lasne、Jacques Rouden
DOI:10.1016/j.tet.2006.04.062
日期:2006.6
Enantioenriched pipecolic esters were prepared in good yields in the decarboxylation, at room temperature, of N-protected piperidinohemimalonates catalyzed by cinchona alkaloids. Enantiomeric excesses as high as 72% were obtained when using 9-epi-cinchonine and the N-benzoyl substituted piperidinohemimalonate. A detailed study of the different reaction parameters revealed that the selectivity of this
在室温下,由金鸡纳生物碱催化的N-保护的哌啶子基亚棉酸酯的脱羧反应中,以高收率制备了富含对映体的胡椒酸酯。当使用9-表位-辛可宁和N-苯甲酰基取代的哌啶子亚氨基甲酸酯时,对映体过量高达72%。对不同反应参数的详细研究表明,这种非共价有机催化反应的选择性很大程度上取决于溶剂,最好的溶剂是甲苯或四氯化碳。基于丙二酸合成的整个过程已成功地在10 mmolar规模上进行了测试,并为烯醇酸锂的不对称质子化建立了实用的替代方法。