Department of Chemistry, University of California, Berkeley, CA, 94720, USA.
Angew Chem Int Ed Engl. 2017 Jul 17;56(30):8887-8891. doi: 10.1002/anie.201704354. Epub 2017 Jun 27.
Enantioselective allylic substitution with enolates derived from aliphatic esters under mild conditions remains challenging. Herein we report iridium-catalyzed enantioselective allylation reactions of silyl ketene acetals, the silicon enolates of esters, to form products containing a quaternary carbon atom at the nucleophile moiety and a tertiary carbon atom at the electrophile moiety. Under relatively neutral conditions, the allylated aliphatic esters were obtained with excellent regioselectivity and enantioselectivity. These products were readily converted into primary alcohols, carboxylic acids, amides, isocyanates, and carbamates, as well as tetrahydrofuran and γ-butyrolactone derivatives, without erosion of enantiomeric purity.
在温和条件下，由脂肪族酯衍生的烯醇盐进行对映选择性烯丙基取代仍然具有挑战性。在此，我们报告了手性铱催化的硅烯醇酯（酯的硅烯醇盐）的对映选择性烯丙基化反应，形成了产物，其中亲核部分含有季碳原子，而亲电部分含有叔碳原子。在相对中性的条件下，以优异的区域选择性和对映选择性得到了烯丙基化的脂肪族酯。这些产物可以很容易地转化为伯醇、羧酸、酰胺、异氰酸酯和氨基甲酸酯，以及四氢呋喃和γ-丁内酯衍生物，而对映体纯度没有降低。
