Organocatalytic Enantio‐ and Diastereoselective Diels‐Alder Reaction between 2,4‐Dienals and α,β‐Unsaturated Esters
作者:Byungjun Kim、Sukwoo Lee、Sarah Yunmi Lee
DOI:10.1002/adsc.202300756
日期:2023.11.21
in the development of catalytic asymmetric Diels-Alder reactions, introducing α,β-unsaturated esters as dienophiles remains challenging owing to their low reactivity. Herein, we report that a chiral aminocatalyst in conjunction with a chiral isothiourea catalyst or a Brønsted acid can promote enantio- and diastereoselective Diels-Alder reactions between 2,4-dienals and α,β-unsaturated esters. This
尽管催化不对称狄尔斯-阿尔德反应的发展取得了进展,但引入α,β-不饱和酯作为亲二烯体仍然具有挑战性,因为它们的反应活性较低。在此,我们报道手性氨基催化剂与手性异硫脲催化剂或布朗斯台德酸结合可以促进2,4-二醛和α,β-不饱和酯之间的对映选择性和非对映选择性狄尔斯-阿尔德反应。该方法通过形成手性三烯胺中间体来与活化的亲二烯体、α,β-不饱和酰基铵物质或质子化的N-杂芳基取代的烯烃进行外环加成。通过二烯和酯亲二烯体的协同活化,可以得到具有多个立构中心的密集官能化环己烯,其dr高达>25:1,ee>99%。此外,我们表明手性催化剂的构型和烯烃几何形状的变化允许对映体纯外型产物的四种立体异构体的立体发散制备。