Lithium derivatives from enantiomerically pure 2-(2′-haloethyl) dioxolanes: Formation and use as chiral propanal homoenolate synthons
作者:María García-Valverde、Rafael Pedrosa、Martina Vicente
DOI:10.1016/0957-4166(95)00225-e
日期:1995.7
corresponding 2-(2′-chloroethyl-)- and 2-(2′-bromoethyl)dioxolanes that were converted into the Li-derivatives by transhalometallation with t-butyllithium in excellent yields. These chiral propanal homoenolates react with benzaldehyde and acetophenone yielding carbinols in moderate chemical yields and low diastereomeric excesses.
3-氯-和3-溴丙醛的缩醛与(-)-1,4-di-O-苄基-L-苏糖醇和(-)-顺-2,3-降冰片二醇的缩合反应生成相应的2-(2通过与叔丁基锂的反式卤化金属转化为Li衍生物的'-氯乙基-)-和2-(2'-溴乙基)二氧戊环具有极高的收率。这些手性丙醛均烯酸酯与苯甲醛和苯乙酮反应,可产生中等化学产率和低非对映异构体过量的甲醇。