Department of Chemistry , University of Toronto , 80 St. George Street , Toronto , Ontario M5S 3H6 , Canada.
Org Lett. 2018 Sep 7;20(17):5327-5331. doi: 10.1021/acs.orglett.8b02248. Epub 2018 Aug 15.
A new mode of catalysis of the semipinacol rearrangement of 2,3-epoxy alcohols is described. In combination with a halide salt additive, diarylborinic acids promote a Type II rearrangement that occurs with net retention of configuration. This unusual stereochemical outcome is consistent with a mechanism involving regioselective ring opening of the epoxy alcohol by halide, followed by rearrangement of the resulting halohydrin-derived borinic ester. The protocol is applicable to a range of substrates, enabling ring contractions and expansions as well as stereospecific syntheses of acyclic β-hydroxycarbonyl compounds.
描述了一种 2,3-环氧醇的半频哪醇重排的新型催化模式。与卤化物盐添加剂结合，二芳基硼酸促进发生构型净保留的 II 型重排。这种不寻常的立体化学结果与一种机制一致，该机制涉及卤化物对环氧醇的区域选择性开环，然后重排得到的卤代醇衍生的硼酸酯。该方案适用于一系列底物，能够实现环收缩和扩张以及非环β-羟基羰基化合物的立体特异性合成。
