Synthesis of 3-Alkoxyalkanoic Esters from Acetals. A Novel Application of Reformatsky Reagents in Asymmetric Synthesis
作者:Tiziana Basile、Emilio Tagliavini、Claudio Trombini、Achille Umani-Ronchi
DOI:10.1055/s-1990-26859
日期:——
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。