3-Alkoxyalkanoic esters are directly obtained in high yield from the reaction of acetals with Reformatsky reagents in the presence of titanium(IV) chloride or diethyl ether-boron trifluoride complex in dichloromethane. The reaction of ethyl 4-bromo-2-butenoate is regioselective, affording the product formed by attack on the 4-position. With chiral acetals as substrates, up to 84% enantiomerically enriched 3-hydroxyalkanoic esters can be prepared.
3-烷氧基烷酸酯通过在
四氯化钛或
二氯甲烷中的二
乙醚-
三氟化硼复合物存在下,
乙缩醛与Reformatsky试剂反应直接高产率地获得。乙基4-
溴-
2-丁烯酸酯的反应具有区域选择性,产物是由对4-位点的进攻形成的。以手性
乙缩醛为底物时,可以制备出最高达84%的具有对映体富集的3-羟基烷酸酯。