Chiral organoaluminum complex 1 efficiently catalyzed the asymmetric hetero-ene reaction of commercially available 2-methoxypropene (2) with aldehydes under mild conditions to give the corresponding β-hydroxymethyl ketones 3 in good to excellent chemical yields with high enantiomeric excesses. The asymmetriccatalysis of 1 was further applied to the carbonyl addition of methallylsilanes, where exclusive
Improved Conditions for the Proline-Catalyzed Aldol Reaction of Acetone with Aliphatic Aldehydes
作者:Benjamin List、Alberto Martínez、Kristina Zumbansen、Arno Döhring、Manuel van Gemmeren
DOI:10.1055/s-0033-1340919
日期:——
The proline-catalyzed asymmetric aldol reaction between aliphatic aldehydes and acetone has, to date, remained underdeveloped. Challenges in controlling this reaction include avoiding undesired side reactions such as aldol condensation and self-aldolization. In recent years we have developed optimized conditions, which enable high yields and good to excellent enantioselectivities, and which are presented
Chiral 1,3-oxazolidines are readily prepared from methyl ketones and chiral norephedrine. Formation of stannous azaenolates from the oxazolidines and reaction with aldehydes followed by removal of the chiral auxiliary lead to the aldol products in high level of enantiomeric purity.