Desymmetrization of diols by a tandem oxidation/Wittig olefination reaction
作者:David J. Phillips、Kathryn S. Pillinger、Wei Li、Angela E. Taylor、Andrew E. Graham
DOI:10.1039/b602329k
日期:——
Diols are desymmetrized by a tandem oxidation/Wittig olefination to give alpha,beta-unsaturated hydroxy esters without the requirement for protecting group strategies; the alpha,beta-unsaturated hydroxy esters are transformed into dienyl diesters using a second oxidation/Wittig olefination sequence using PCC.
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.
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
A Regio- and Diastereoselective Intramolecular Nitrone Cycloaddition for Practical 3- and 2,3-Disubstituted Piperidine Synthesis from γ-Butyrolactone
作者:Benjamin E. Stephens、Fei Liu
DOI:10.1021/jo8018285
日期:2009.1.2
3-disubstituted piperidines, featuring an intramolecular nitronecycloaddition with high regio- and diastereoselectivity, was achieved in six steps and 36−66% overall yield from commercially available γ-butyrolactone or 1,4-butanediol. A new N-alkenyl nitrone enoate was used in this intramolecular nitronecycloaddition, and the regioselectivity, diastereoselectivity, and reversibility of this cycloaddition were
Coibacins A and B: Total Synthesis and Stereochemical Revision
作者:Vânia M. T. Carneiro、Carolina M. Avila、Marcy J. Balunas、William H. Gerwick、Ronaldo A. Pilli
DOI:10.1021/jo402339y
日期:2014.1.17
The interface between synthetic organic chemistry and natural products was explored in order to unravel the structure of coibacin A, a metabolite isolated from the marine cyanobacterium cf. Oscillatoria sp. that exhibits selective antileishmanial activity and potent anti-inflammatory properties. Our synthetic plan focused on a convergent strategy that allows rapid access to the desired target by coupling of three key fragments involving E-selective Wittig and modified Julia olefinations. CD measurements and comparative HPLC analyses of the natural product and four synthetic stereoisomers led to determination of its absolute configuration, thus correcting the original assignment at C-5 and unambiguously establishing those at C-16 and C-18. Additionally, we synthesized coibacin B on the basis of the assignment of configuration for coibacin A.