Site-Selective Mono-Oxidation of 1,2-Bis(boronates)
作者:Lu Yan、James P. Morken
DOI:10.1021/acs.orglett.9b01204
日期:2019.5.17
Site-selective oxidation of vicinal bis(boronates) is accomplished through the use of trimethylamineN-oxide in 1-butanol solvent. The reaction occurs with good efficiency and selectivity across a range of substrates, providing 2-hydro-1-boronic esters which are shown to be versatile intermediates in the synthesis of chiral building blocks.
Highly Selective Hydrolytic Kinetic Resolution of Terminal Epoxides Catalyzed by Chiral (salen)Co<sup>III</sup> Complexes. Practical Synthesis of Enantioenriched Terminal Epoxides and 1,2-Diols
作者:Scott E. Schaus、Bridget D. Brandes、Jay F. Larrow、Makoto Tokunaga、Karl B. Hansen、Alexandra E. Gould、Michael E. Furrow、Eric N. Jacobsen
DOI:10.1021/ja016737l
日期:2002.2.1
The hydrolytickineticresolution (HKR) of terminal epoxides catalyzed by chiral (salen)Co(III) complex 1 x OAc affords both recovered unreacted epoxide and 1,2-diol product in highly enantioenriched form. As such, the HKR provides general access to useful, highly enantioenriched chiral building blocks that are otherwise difficult to access, from inexpensive racemic materials. The reaction has several
Methanesulfonamide: a Cosolvent and a General Acid Catalyst in Sharpless Asymmetric Dihydroxylations
作者:Mikko H. Junttila、Osmo O. E. Hormi
DOI:10.1021/jo8026998
日期:2009.4.17
effect on the reaction time and methanesulfonamide effect. The more polar the intermediate osmate ester, the faster is the reaction without methanesulfonamide and the smaller the accelerating methanesulfonamide effect. Methanesulfonamide had no accelerating effect in the asymmetric dihydroxylation of short chain terminal aliphatic olefins as a result of easier accessibility of terminal osmate ester
De Novo Synthesis of a <scp>d</scp>-Galacturonic Acid Thioglycoside as Key to the Total Synthesis of a Glycosphingolipid from <i>Sphingomonas </i><i>yanoikuyae</i>
作者:Pierre Stallforth、Alexander Adibekian、Peter H. Seeberger
DOI:10.1021/ol800227b
日期:2008.4.1
A concise synthesis of a differentiallyprotected D-galacturonic acid (D-GalA) thioglycoside and the construction of a potent immunomodulating glycosphingolipid are described. The key steps of the synthesis are an Evans aldol reaction between a C4 aldehyde and a PMB-protected glycolyloxazolidinone as well as a tandem-PMB-deprotection/cyclization to thioglycosides. The key glycosylation step is optimized
Systematic Construction of a Monotetrahydrofuran-Ring Library inAnnonaceous Acetogenins by Asymmetric Alkynylation and Stereodivergent Tetrahydrofuran-Ring Formation
diastereoisomers of the monotetrahydrofuran-ring cores of annonaceousacetogenins have been synthesized through utilization of asymmetric alkynylation and stereodivergent one-pot tetrahydrofuran-ring formation. In all cases, the asymmetric alkynylation proceeded with very high diastereoselectivity to give eight kinds of optically pure tetrahydrofuran core from a common alpha-oxyaldehyde. We also describe