Diastereoselective desymmetrization of diarylphosphinous acid-borane amides under Birch reduction
作者:Marek Stankevič
DOI:10.1039/c4ob02440k
日期:——
Treatment of diarylphosphinous acid-borane amides possessing chiral amido functionality with an alkali metal solution in liquid ammonia induced a preferential dearomatization of one aryl substituent at phosphorus leading to the formation of non-equimolar amounts of diastereomers. Diastereoselectivity of dearomatization depends strongly on the structure of a chiral auxiliary.
Sulfonyl Compound as Inhibitors of 11-Beta-Hydroxysteroid Dehydrogenase-1
申请人:Waddell Sherman T.
公开号:US20080318930A1
公开(公告)日:2008-12-25
Sulfonyl derivatives of structural formula I are selective inhibitors of the 11β-hydroxysteroid dehydrogenase-1. The compounds are useful for the treatment of diabetes, such as noninsulin-dependent diabetes (NIDDM), hyperglycemia, obesity, insulin resistance, dyslipidemia, hyperlipidemia, hypertension, Metabolic Syndrome or Syndrome X, and other symptoms associated with NIDDM.
1,5-Asymmetric Induction in Squarate Cascades. Conformational Control of Helicity by Chiral Amino Substituents during Conrotatory Octatetraene Cyclization Prior to β-Elimination
作者:Leo A. Paquette、Jinsung Tae
DOI:10.1021/jo9722921
日期:1998.3.1
Both the sigmatropic and electrocyclic rearrangement pathways that can arise when a pair of alkenyl anions are added to a squarate ester have high stereochemical demands. The distinction is nontrivial. When cis addition occurs initially, the stereoinduction that materializes at this point is fully transmitted into the product(s). The more commonly observed trans addition exhibits fleeting stereochemical consequences because of rapid equilibration of the octatetraenyl intermediates. In this instance, product distribution is governed by the relative rates of conrotatory cyclization at this advanced stage. Herein reported is a complete dissection of a squarate cascade when a stereogenic center attached to an amino substituent effects 1,5-asymmetric induction prior to B-elimination of the entire fragment. Deuterium labeling permits a direct measure of the contrasting kinetic imbalances associated with the two possible modes of alkenyl anion addition. Furthermore; quantitative analysis of the partitioning experienced by the two helical octatetraenes is readily accomplished. This work constitutes the first example where a complete dynamic profile for these complex processes has been possible. The fact that long-range asymmetric induction has been instrumental in solving the mechanistic puzzle is noteworthy.
Wegler; Rueber, Chemische Berichte, 1935, vol. 68, p. 1055,1057
作者:Wegler、Rueber
DOI:——
日期:——
Forster, Journal of the Chemical Society, 1899, vol. 75, p. 942,1152,1153