perform hydroxylations with substrate selectivity and regio- and stereoselectivity and high catalytic turnovers. The geometries of the catalyst/substrate complexes override intrinsic substrate reactivities, permitting attack on geometrically accessible saturated carbons of steroids in the presence of secondary carbinol groups and carbon-carbon double bonds, as in enzymatic reactions. Selective hydroxylations
Prochiral recognition in the reaction of 3-substituted glutaric anhydrides with chiral secondary alcohols
作者:Peter D. Theisen、Clayton H. Heathcock
DOI:10.1021/jo00053a027
日期:1993.1
The scope of a previously-reported process for the desymmetrization 3-substituted glutaric anhydrides has been investigated. Thus, prochiral anhydrides 5-9 react with 1-(1'-naphthyl)ethanol (2) to give glutaric acid half-esters, which are esterified by treatment with diazomethane to obtain the corresponding diesters 16-20. The degree of prochiral recognition is inversely related to the steric bulk of the stereodifferentiating group, with the series TBDMSO, Me, Et, Ph, i-Pr, and t-Bu giving ratios of 40:1, 16:1, 14:1, 8:1, 7:1, and 1:3, respectively. The absolute sense of the prochiral recognition was established by conversion of two of the diesters, 16a and 18a, into 3-substituted valerolactones (22a, 22c) of known absolute configuration.
Enantioselective Desymmetrization of Glutarimides Catalyzed by Oxazaborolidines Derived from <i>cis</i>-1-Amino-indan-2-ol
作者:Ibrahim U. Kutama、Simon Jones
DOI:10.1021/acs.joc.5b02177
日期:2015.11.20
Enantioselective reductive desymmetrization of glutarimides,has been achieved employing an oxazaborolidine catalyst derived from cis-1-amino-indan-2-ol. The reaction was found to proceed through a stereoablative process, that upgraded the enantioselectivity of an intermediate,hydroxy-lactam. The reaction: was generally tolerant of a number of substituents in the 4-position giving enantiomeric excesses of greater than 82%.
Stereochemistry of chlorination of thiane 1-oxides
作者:J. Klein、H. Stollar
DOI:10.1021/ja00803a037
日期:1973.10
Theisen Peter D., Heathcock Clayton H., J. Org. Chem., 58 (1993) N 1, S 142-146