1,2-Dioxines as Masked Cis γ-Hydroxy Enones and Their Versatility in the Synthesis of Highly Substituted γ-Lactones
作者:Ben W. Greatrex、Marc C. Kimber、Dennis K. Taylor、Gary Fallon、Edward R. T. Tiekink
DOI:10.1021/jo0200421
日期:2002.7.1
Heterolytic or homolytic cleavage of the 1,2-dioxines under appropriate conditions generates the key reactive cis gamma-hydroxy enones, which ultimately afford the observed gamma-lactones. Diastereoselectivity is installed as a result of anti 1,4-addition by the ester enolate to the cis enones followed by intramolecular cyclization. The reaction is tolerant of a range of substitution patterns on the 1,2-dioxine
将高度稳定的酯亲核试剂加到1,2-二恶英中可提供高非对映选择性的高产率的γ-内酯。1,2-二恶英在适当条件下的异源或同源裂解产生关键的反应性顺式γ-羟基烯酮,最终提供了观察到的γ-内酯。非对映选择性是由于酯烯醇盐将其抗1,4-加成至顺式烯酮,随后进行分子内环化而导致的。该反应可耐受1,2-二恶英上的一系列取代模式,同时还可容纳多种酯。除了外消旋γ-内酯的合成外,当手性钴(II)催化剂用于1,2-二恶英的初始均相开环时,还可以合成高度对映体富集的γ-内酯。