First Asymmetric Synthesis of Quinoline Derivatives by Inverse Electron Demand (IED) Diels−Alder Reaction Using Chiral Ti(IV) Complex

Abstract

[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 facile route for the synthesis of asymmetric tetrahydroquinoline derivatives using the above-mentioned chiral catalyst reagent in the presence of 4 A molecular sieves. The reactions proceed with moderate yields and at times high enantioselectivty.