Stereoselective addition of 1,3-diketones to β-Nitroacrylates catalyzed by chiral metal-free bifunctional catalysts

Organocatalytic stereoselective additions of different nucleophiles to β-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 N-methylindole 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.