The influence of α-coordinating groups of aldehydes on <i>E</i>/<i>Z</i>-selectivity and the use of quaternary ammonium counter ions for enhanced <i>E</i>-selectivity in the Julia–Kocienski reaction
Modified reaction conditions for improved E-selectivity of olefins in the Julia–Kocienski reaction of aldehydes having α-coordinating substituents are demonstrated. The chelating groups in aldehydes are expected to stabilize the syn-transition state with metal ions, whereas the weakly coordinating quaternary ammonium ions are devoid of all possible chelating interactions to enhance E-selectivity. A
Stereoselective synthesis of (6S) and (6R)-5,6-dihydro-6-[(2R)-2-hydroxy-6-phenylhexyl]-2H-pyran-2-one and their cytotoxic activity against cancer cell lines
作者:Manchala Narasimhulu、Arepalli Sai Krishna、Janapala Venkateswara Rao、Yenamandra Venkateswarlu
DOI:10.1016/j.tet.2009.01.101
日期:2009.4
Stereoselectivetotalsynthesis of α,β-unsaturated lactone (1a), isolated from Ravensara crassifolia, has been achieved efficiently starting from chiral 2,3-O-isopropylidene-d-glyceraldehyde (3) followed by asymmetric allylation and ring-closing metathesis. The antiproliferative activities of compounds 1a, 1b and the unusual bicyclic compound 2 were evaluated against three-cancer cell lines, THP-1
Olefination of α-Hydroxy or α-Aminoaldehyde Derivatives via Reaction of Their Arylsulfonylhydrazones with Sulfonyl Anions
作者:Jerzy Wicha、Andrzej Zarecki
DOI:10.1021/jo0499118
日期:2004.8.1
Reaction of tosylhydrazones of O-substituted a-hydroxy or N-substituted a-amino aldehydes (2, 7, 11, 15, 17, and 20) with selected alpha-magnesio alkyl phenyl sulfones afforded the respective derivatives of allylic alcohols or allylic amines. 2,3-O-Isopropylidene-D-glyceraldehyde (1) was transformed into its tosylhydrazone (2) and then olefins 4a with retention of optical purity.