The first example of enantioselective carbenoid addition to organochalcogen atoms: application to [2,3]sigmatropic rearrangement of allylic chalcogen ylides
作者:Yoshiaki Nishibayashi、Kouichi Ohe、Sakae Uemura
DOI:10.1039/c39950001245
日期:——
a carbenoid, derived from ethyl diazoacetate, to chalcogen atoms of aryl cinnamyl chalcogenides affords a diastereoisomeric mixture of ethyl 2-arylchalcogeno-3-phenylpent-4-enoates via[2,3]sigmatropicrearrangement of the intermediate chalcogen ylide with up to 41% ee.
chiral 1-phenyl-2-propen-1-ol via asymmetric [2,3] sigmatropicrearrangement in a moderate to high enantiomeric excess (up to 92% e.e.). The enantioselectivity was found to be enhanced remarkably by the introduction of the o-nitro group to an arylseleno moiety of the substrate and the use of diisopropyl tartrate (DIPT) ligand in the Sharpless oxidant. In the rearrangement stop two possible transition
Vanadium-catalyzed selenide oxidation with in situ [2,3] sigmatropic rearrangement (SOS reaction): scope and asymmetric applications
作者:T. Campbell Bourland、Rich G. Carter、Alexandre F. T. Yokochi
DOI:10.1039/b316502g
日期:——
A vanadium-catalyzed method for the oxidation of prochiral aryl, allylic selenides with tandem [2,3] sigmatropic rearrangement has been developed. This protocol has been screened on a series of substrates to test for its generality and effectiveness. The applicability of this methodology to the synthesis of enantiomerically enriched allylic alcohols has been studied on a series of chiral oxazole-containing