An Entry to a Chiral Dihydropyrazole Scaffold: Enantioselective [3 + 2] Cycloaddition of Nitrile Imines
摘要:
We have developed a versatile strategy to access dihydropyrazoles in highly enantioenriched form. Dipolar cycloaddition of electron-deficient acceptors and in situ-generated nitrile imines proceeds with high regio- and enantioselectivity using 10 mol % chiral Lewis acid catalyst. A variety of dihydropyrazoles that incorporate functionality for further manipulation have been prepared.
Enantioselective Diels–Alder reactions of 3-(acyloxy)acrylates
作者:Mukund P. Sibi、Hirofumi Matsunaga
DOI:10.1016/j.tetlet.2004.05.090
日期:2004.7
Diels-Alder reactions with 3-(acyloxy)acrylates using chiral Lewis acid catalysts have been successfully carried out. These reactions proceed with high enantioselectivity when a chiral Lewis acid derived from Cu(OTf)(2) and a bisoxazoline is used. The facility of the reaction is dependent on the nature of the acyloxy group in the dienophile. (C) 2004 Elsevier Ltd. All rights reserved.