Modulating the stereochemical outcome of the Ireland–Claisen reaction of (E)- and (Z)-allylic glycolates
作者:Ken S. Feldman、Brandon R. Selfridge
DOI:10.1016/j.tetlet.2011.12.011
日期:2012.2
The diastereoselectivity of Ireland–Claisen rearrangements of allylic glycolates is dependent on the E:Z ratio of the silyl ketene acetals, the alkene geometry in the allyl unit, and the transition state topography. High yields and excellent diastereoselectivities (>95:5) have been achieved for selected substrates, including those with R2 = ethyl that results in a newly formed quaternary center. A
烯丙基乙醇酸酯的爱尔兰-克莱森重排的非对映选择性取决于甲硅烷基烯酮缩醛的E:Z比,烯丙基单元中的烯烃几何形状以及过渡态的形貌。对于选定的底物,包括那些具有R 2 =乙基的底物,它们会导致新形成的四元中心,已实现了高收率和出色的非对映选择性(> 95:5)。将讨论范围,选择性和过渡状态模型。