کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5268782 | 1385372 | 2014 | 4 صفحه PDF | دانلود رایگان |
Starting from (E)-β-substituted-β-nitroacrylates and α,β-unsaturated ketones, a stereoselective organocatalyzed one-pot methodology allowed to synthesize highly decorated chiral 2-nitro-cyclohexane carboxylic esters. The reaction is promoted by Cinchona alkaloid-derived primary amines in the presence of an acidic co-catalyst and affords two diastereoisomers, in good yields and high enantiomeric excess (often higher than 90% ee). By replacing conventional heating with microwave irradiation, cleaner reactions in shortened times (from 48 h to 30 min) were obtained, with improved dr (80:20) and high ee (up to 94%). The application of microwave technology to this organocatalytic methodology allowed also employing C1 substituted enones, leading to cyclohexanones with four contiguous stereocenters in two isomers only, and up to 99% enantioselectivity.
Journal: Tetrahedron Letters - Volume 55, Issue 49, 3 December 2014, Pages 6639-6642