In Situ Generation of Ylides for Tandem Oxidation-Olefination Reactions of Unactivated Diols
作者:Andrew Graham、David Phillips
DOI:10.1055/s-2008-1042799
日期:——
An efficient desymmetrization of diols is achieved using phosphonium salts which undergo deprotonation in the presence of a hindered amine base and manganese dioxide to produce α,β-unsaturated hydroxy esters in good yields.
Extended Stereocontrol in Silyl Group-Transfer Cyclizations: Control of Four Contiguous Chiral Centers
作者:Peter G. Klimko、Daniel A. Singleton
DOI:10.1055/s-1994-25618
日期:——
The potential for extended stereocontrol in silyl group-transfer cyclizations was explored in model studies which formed four contiguous chiral centers. The diastereofacial selectivity for the reaction of cyclized intermediates was outstanding for both fluoride and SnCl2 trityl chloride mediated reactions. Good simple diastereoselectivity was observed in reactions initiated by prochiral silyl enolates.
Diol desymmetrization as an approach to the synthesis of unsymmetrical dienyl diesters
作者:David J. Phillips、Kathryn S. Pillinger、Wei Li、Angela E. Taylor、Andrew E. Graham
DOI:10.1016/j.tet.2007.07.089
日期:2007.10
The tandem oxidation/Wittig olefination of unactivated diols utilizing manganese dioxide produces α,β-unsaturated hydroxy esters in high yields in a highly effective desymmetrization process. The formation of small quantities of the corresponding lactones suggests that the reaction may proceed through a lactol intermediate in some cases. The α,β-unsaturated hydroxy esters are transformed into symmetrical
Cyclisation of α,β,γ,ψ-unsaturated dioic acid esters via tandem conjugate additions by using lithium N-benzyltrimethylsilylamide (LSA) as a nitrogen nucleophile and its application to a total synthesis of (±)-dihydronepetalactone and (±)-isodihydronepetalactone
作者:Tadao Uyehara、Naomi Shida、Yoshinori Yamamoto
DOI:10.1039/c39890000113
日期:——
A stereoselective totalsynthesis of (±)-dihydronepetalactone and (±)-isodihydronepetalactone has been accomplished by utilising a novel cyclisation procedure; a reaction of octadiene-2,6-dioic acidesters with lithiumN-benzyltrimethylsilylamide (LSA) induces 5-exo-Trig ring-closure viatandemconjugateadditions.