α‐ and β‐Lipomycin: Total Syntheses by Sequential Stille Couplings and Assignment of the Absolute Configuration of All Stereogenic Centers
作者:Max L. Hofferberth、Reinhard Brückner
DOI:10.1002/anie.201402255
日期:2014.7.7
structures of α‐lipomycin and its aglycon β‐lipomycin except for the configurations of their side‐chain stereocenters. We synthesized all relevant β‐lipomycin candidates: the (12R,13S) isomer has the same specific rotational value as the natural product. By the same criterion the (12R,13S)‐configured D‐digitoxide is identical to α‐lipomycin. We double‐checked our assignments by degrading α‐ and β‐lipomycin
The Exceptional Chelating Ability of Dimethylaluminum Chloride and Methylaluminum Dichloride. The Merged Stereochemical Impact of α- and β-Stereocenters in Chelate-Controlled Carbonyl Addition Reactions with Enolsilane and Hydride Nucleophiles
作者:David A. Evans、Brett D. Allison、Michael G. Yang、Craig E. Masse
DOI:10.1021/ja011337j
日期:2001.11.1
beta-disubstituted aldehydes concludes that the syn aldehyde diastereomer possesses the arrangement of stereocenters wherein the alpha- and beta-substituents impart a reinforcing facial bias upon the aldehyde carbonyl. Aldol reactions of syn aldehydes were thus observed to proceed with uniformly excellent diastereofacial selectivity. Aldol reactions of the corresponding anti aldehydes containing opposing