Abstract:The aldol-type addition to ketones still represents a great challenge in asymmetric catalysis. Recently, the direct aldol reaction between the commercially available ethyl diazoacetate and aldehydes has attracted increasing attention. Ethyl diazoA C H T U N G T R E N N U N G acetate is economical and allows further transformation of the aldol adduct obtained. We present a solution for the arduous, and not previously described, addition of diazoacetate to ketones. Our procedure employs commercially available nor-A C H T U N G T R E N N U N G ephedrine-derived ligands and dialkylzinc reagents [R 2 Zn: (diethylzinc, Et 2 Zn; dimethylzinc, Me 2 Zn)] as starting materials, therefore the active catalyst is prepared with a very straightforward methodology. Remarkably, the reaction gives good enantiomeric excesses with a-halo ketones, a class of compounds that has not been commonly used in enolate addition.
Azo compounds Q 0160The First Catalytic Enantioselective Aldol-Type Reaction of Ethyl Diazoacetate to Ketones. -The catalytic asymmetric addition of an enolate to α-haloketones is realized for the first time in course of this study.
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