作者:Anna Lee、Anna Michrowska、Sarah Sulzer-Mosse、Benjamin List
DOI:10.1002/anie.201006319
日期:2011.2.11
116 years after the discovery of the Knoevenagelcondensation, the first catalyticasymmetric variant has been developed. Dynamic kinetic resolution in the reaction of α‐branched aldehydes with malonates in the presence of a newly designed and readily available modified cinchona amine catalyst gives the corresponding alkylidene malonates in high enantioselectivity (see scheme).
A photoenzymaticstrategy for radical-mediated stereoselectivehydroalkylation with diazocompounds has been developed. By this method, a series of γ-chiral carbonyl compounds were synthesized in high yields and stereoselectivities.
different α-branched aldehydes were treated with various malonate derivatives to give enantiomerically enriched Knoevenagel products with higher chemical yield (up to 97%) and excellent e.r up to 99.68 0.32 via dynamic kinetic resolution. Further the Knoevenagel adduct was converted into enantiomerically enriched valuable γ-alkyl-substituted amides without loss in enantiomeric ratio.