A Short and Convenient Synthesis of Enantiopure cis- and trans-4-Hydroxypipecolic Acid
作者:Ernesto Occhiato、Cristina Prandi、Dina Scarpi、Antonio Guarna、Silvia Tabasso、Annamaria Deagostino
DOI:10.1055/s-0029-1216979
日期:2009.11
The synthesis of (2S,4R)- and (2R,4R)-4-hydroxypipecolic acid has been realized from commercial ethyl (R)-4-cyano-3-hydroxybutanoate through palladium-catalyzed methoxycarbonylation of a 4-hydroxy-substituted lactam-derived vinyl phosphate followed by the stereocontrolled reduction of the enamine double bond. The stereoselective hydrogenation of the suitably 4-hydroxy-protected enantiomer afforded
(2 S,4 R)-和(2 R,4 R)-4-羟基哌酸的合成已由商业化(R)-4-氰基-3-羟基丁酸乙酯通过钯催化4-的甲氧基羰基化而实现羟基取代的内酰胺衍生的磷酸乙烯酯,然后立体控制还原烯胺双键。适当地4-羟基保护的对映异构体的立体选择性氢化提供了顺式-(2 S,4 R)-4-羟基哌酸产物,在七个步骤中以66%的总收率获得。该反式而是通过将氢化物共轭加成到相同的α,β-不饱和酯中而得到产物(8个步骤中总产率为42%)。 氨基酸-羰基化-偶联-内酰胺-钯