promoted pinacol cross coupling of a chiral aromatic aldehyde with chiral aliphatic aldehydes occurs to afford diols in up to 91:9 diastereoisomeric ratio and up to 84% enantiomeric excess. The pinacol coupling of (S)-lactaldehyde and (R)-glyceraldehyde derivatives has also been studied and matching and mis-matching pairs have been identified. The stereochemistry of the products was established by correlation
Enantioselective and Rapid Rh-Catalyzed Arylation of <i>N</i>-Tosyl- and <i>N</i>-Nosylaldimines in Methanol
作者:Chun-Chih Chen、Balraj Gopula、Jin-Fong Syu、Jhih-Han Pan、Ting-Shen Kuo、Ping-Yu Wu、Julian P. Henschke、Hsyueh-Liang Wu
DOI:10.1021/jo5012653
日期:2014.9.5
Enantiomericallyenriched tosyl-protected diarylmethylamines were rapidly prepared by the asymmetricaddition of arylboronic acids to N-tosylaldimines under mild conditions in the presence of a catalyst prepared in situ from Rh(I) and a chiral diene ligand. This methodology offers access to diarylmethylamines in good yields with excellent chiral purity at room temperature using MeOH as a solvent and
Highly Diastereoselective 5-Hexenyl Radical Cyclizations with Lewis Acids and Carbohydrate Scaffolds
作者:Eric J. Enholm、Jennifer S. Cottone、Florent Allais
DOI:10.1021/ol006651h
日期:2001.1.1
[figure: see text] Carbohydrates as removable chiral scaffolds for free radical cyclizations were examined for the first time. This investigation illustrates the utility of two inexpensive carbohydrate derivatives as sources of asymmetry for 5-hexenyl radical cyclizations. Diastereomeric ratios as high as 100:1 were achieved with an ester-appended (+)-isosorbide hexose and 70:1 for a diol-protected