Organocatalytic stereoselective additions of different nucleophiles to b-nitroacrylates have been investigated. A thiourea-based cinchona-derived bifunctional catalyst promotes the addition of 1,3-diketones to differently substituted nitroacrylates in modest to fair yields and up to 93% enantioselectivity. The 1,3 dicarbonyl functionality of the addition products was then used to synthesize enantiomerically enriched 3,4,5-trialkyl substituted pyrazoles via reaction with hydrazine. The stereoselective addition of Nmethylindole to nitroacrylate was also preliminarily studied; the Friedel–Crafts alkylation was successfully organocatalyzed in the presence of an acid additive in very good yields and up to 53% enantioselectivity.
|Titolo:||Stereoselective Addition of 1,3-Diketones to b-Nitroacrylates Catalyzed by Chiral Metal-Free Bifunctional Catalysts|
|Data di pubblicazione:||2014|
|Appare nelle tipologie:||Articolo|