To provide new optically-active β-hydroxy-α-bromo-α-fluorocarboxylates which are expected to be useful as synthetic intermediates of physiologically-active substances and a process for catalytic preparation of these optically-active substances in high asymmetric yield, and further to provide new 2-bromo-2-fluoroketenesilylacetals which are also useful as synthetic intermediates of these optically-active substances and a synthetic process thereof.
New optically-active β-hydroxy-α-bromo-α-fluorocarboxylates are prepared by catalytic asymmetric synthesis wherein new 2-bromo-2-fluoroketenesilylacetals, which are obtained by reacting dibromofluoroacetates with halogenated silyl compounds, are reacted with aldehydes in the presence of a catalytic amount of chiral Lewis acid.
提供有望用作生理活性物质合成中间体的新型光学活性β-羟基-α-
溴-α-
氟羧酸盐,以及催化制备这些光学活性物质的高不对称产率工艺,并进一步提供也可用作这些光学活性物质合成中间体的新型 2-
溴-2-
氟酮烯
硅烷乙醛及其合成工艺。
新的光学活性 β-羟基-α-
溴-α-
氟羧酸盐是通过催化不对称合成法制备的,其中新的 2-
溴-2-
氟酮烯基
乙醛是通过
二溴氟乙酸盐与卤代
硅化合物反应得到的,在手性
路易斯酸的催化下与醛反应。