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
Chelation-controlled stannylacetylene additions to β-alkoxy aldehydes promoted by alkylaluminum halide Lewis acids
作者:David A. Evans、David P. Halstead、Brett D. Allison
DOI:10.1016/s0040-4039(99)00740-6
日期:1999.6
Lewis acid-mediated additions of stannylacetylenes to β-alkoxy aldehydes are reported. High levels of chelation control are observed with dimethylaluminum chloride (Me2AlCl) and methylaluminum dichloride (MeAlCl2).
Chelate-controlled carbonyl addition reactions. The exceptional chelating abilityof dimethylaluminum chloride and methylaluminum dichloride
作者:David A. Evans、Brett D. Allison、Michael G. Yang
DOI:10.1016/s0040-4039(99)00739-x
日期:1999.6
Highly selective chelatinn-controlled aldol and allyl nucleophile additions to β-alkoxy aldehydes promoted by dimethylaluminum chloride and methylaluminum dichloride are described. Cationic aluminum chelates are proposed as intermediates in these reactions. Evidence is provided to support the claim that chelate organization with Me2AlCl and MeAlCl2 is possible even with β-tert-butyldimethyl-silyloxy
An oxo-hexaene macrolide antibiotic, dermostatin A has been synthesized. Key features of the synthesis include the application of cyanohydrin acetonide couplings for the synthesis of the polyol portion, and the convergent introduction of the polyene segment by means of a Stille coupling.