Sodium Salts of Anionic Chiral Cobalt(III) Complexes as Catalysts of the Enantioselective Povarov Reaction
作者:Jie Yu、Hua-Jie Jiang、Ya Zhou、Shi-Wei Luo、Liu-Zhu Gong
DOI:10.1002/anie.201504790
日期:2015.9.14
The sodium salts of anionic chiral cobalt(III) complexes (CCC−Na+) have been found to be efficient catalysts of the asymmetric Povarov reaction of easily accessible dienophiles, such as 2,3‐dihydrofuran, ethyl vinyl ether, and an N‐protected 2,3‐dihydropyrrole, with 2‐azadienes. Ring‐fused tetrahydroquinolines with up to three contiguous stereogenic centers were thus obtained in high yields, excellent
[reaction: see text] (R,R)-3-Aza-3-benzyl-1,5-dihydroxy-1,5-diphenylpentane (1) ligated Ti(IV) complex (1-TiCl(2)) is used as a chiral Lewis acid catalyst for promoting asymmetric IED Diels-Alder reaction between electron-rich dienophiles and electron-poor dienes. Here we introduce a facileroute for the synthesis of asymmetric tetrahydroquinoline derivatives using the above-mentioned chiral catalyst
ethyl vinyl ether, 2,3‐dihydropyran, and cyclopentadiene can be promoted by ionicliquids like imidazolium salts and guanidiniumsalts under thermal as well as microwave conditions. The chemical yield as well as the diastereoselectivity of the Povarov reaction strongly depend on the ionicliquid employed. The guanidiniumsalts can be recycled and reused several times without loss of reactivity.