A series of new modular bifunctional chiral thiourea organocatalysts were synthesized from natural Cinchona alkaloids and amino acids, and their performance in the aza-Henry reaction of nitroalkanes to imines, the Michaeladdition of acetylacetone to nitroolefins and the Michaeladdition of acetone to nitroolefins was investigated. Under the mild conditions, the important building blocks β-nitro amines
A Novel Bis-Thiourea Organocatalyst for the Asymmetric Aza-Henry Reaction
作者:Constantinos Rampalakos、William D. Wulff
DOI:10.1002/adsc.200800214
日期:2008.8.4
A novelbis-thiourea BINAM-based catalyst for the asymmetricaza-Henryreaction has been developed. This catalyst promotes the reaction of N-Boc imines with nitroalkanes to afford beta-nitroamines with good yields and high enantioselectivities. This catalyst has the advantage that it can be prepared in a single step from commercially available materials. A model is proposed for the catalyst action
Diastereomerically pure tridentate heteroorganic ligands containing hydroxyl, sulfinyl, and amino moieties as nucleophilic centers, capable of binding various organometallic reagents, have proven to be highly efficient catalysts in enantioselective aza-Henry reactions to give the desired products in very high yields (up to 98%) and with ees of up to 95%. The influence of the stereogenic centers, located on the sulfinyl sulfur atom and in the amino moiety on the stereochemical course of the reaction is also discussed. (C) 2011 Elsevier Ltd. All rights reserved.