Regio- and stereoselectivity control in palladium-catalyzed allylic alkylation of 1-cycloalkenylmethyl acetates
作者:Olivier Jacquet、Jean-Yves Legros、Matthieu Coliboeuf、Jean-Claude Fiaud
DOI:10.1016/j.tet.2008.04.059
日期:2008.6
Enantiomerically pure allylic acetates 1a and 1b were obtained by lipase-catalyzed acylation through kinetic resolution processes of the racemates. Palladium-catalyzed alkylation of 1a with dimethyl malonate was both regio- and stereoselective, showing that no isomerization of the acetate 1a or the intermediate π-allylic palladium complex took place under the conditions used. Alkylation of 1b was stereoselective
对映体纯的乙酸烯丙酯1a和1b是通过外消旋体的动力学拆分过程通过脂肪酶催化的酰化作用而获得的。丙二酸二甲酯在钯催化下的1a烷基化具有区域选择性和立体选择性,表明在使用的条件下,乙酸酯1a或中间体π-烯丙基钯配合物没有发生异构化。1b的烷基化是立体选择性的,但不是区域选择性的。区域选择性可以通过手性配体的适当选择被部分地控制。设定条件以同时进行1b的烷基化 然后通过一锅一步法将所得产物脱羰甲氧基化,得到3-(环己-1-烯基)丁酸酯。