Enantioselective Catalytic Carbonyl–Ene Cyclization Reactions

Abstract

Intramolecular ene reactions of simple alkenyl aldehydes are catalyzed by a chiral (Schiff base)CrIII complex with high enantio‐ and diastereoselectivity, affording densely functionalized heterocyclic or carbocyclic products (see scheme for example). Desymmetrizations of alkenyl dialdehydes and bis(alkenyl) aldehydes are also achieved.

2.03 Prins Reactions and Carbonyl, Imine, and Thiocarbonyl Ene Reactions

“…Jacobsen found that Cr(III) complex 183 formed from tridentate Schiff base catalyzes the asymmetric ene reaction of 180 to give 181 and 182 in 85-92% ee. 132 This catalyst is also effective for type I ene reactions leading to five-membered ring alcohols in 77-96% ee and for type II ene reactions leading to sixmembered ring alcohols in 94-95% ee. It is also effective for the type I and type II ene reaction desymmetrization of bis(alkenyl) aldehydes and alkenyl dialdehydes.…”

Chiral Polymetallic Catalysts and Their Applications in Asymmetric Catalysis

“…三齿席夫碱配体与 Cr 的配合物 32 作为手性催化剂 应用于醛的分子间和分子内杂 ene 反应, 取得了很好的 结果, 催化剂的活性和对映选择性都很高. Jacobsen 等 [16] 设计了一系列复杂的可发生分子内 ene 反应的底 物, 32 催化这些底物发生反应得到了非常有用的五元和 六元杂环化合物(Scheme 10). Jacobsen chiral bimetallic catalysts…”

Diastereoselective and enantioselective preparation of nor-mevaldic acid surrogates through desymmetrisation methodology. Enantioselective synthesis of (+) and (−) nor-mevalonic lactones

“…This approach has been successfully applied to the desymmetrisation of a range of substrates such as dienes, 4 mesoanhydrides, 5 meso-diols 6 and meso-dialdehydes. Desymmetrisation of meso-dialdehydes has been performed via Horner-Wadsworth-Emmons reaction, 7 alkylation, 8 carbonyl-ene cyclization reaction 9 and aldol condensation, either using chiral reagents, 10 an organometallic catalyst 11 or organocatalysis. 12 In this respect, the synthetic utility of 1,3,5-trioxygenated substrates has led to much interest in their enantiocontrolled preparation.…”