Anti-Selective Glycolate Aldol Additions with an Oxapyrone Boron Enolate
摘要:
GRAPHICSThe boron enolate of pyrone 2 undergoes asymmetric aldol reactions with aldehydes to give protected anti 1,2 diols 3. The pyrone is readily available from trans stilbene using asymmetric dihydroxylation. Yields for the aldol reaction range from 62 to 92% and the selectivities from 6:1 to >20:1 for the anti isomers, Protection and hydrogenolysis of the products can be used to remove the pyrone, giving differentially protected diol intermediates 12 that are amenable to multistep synthesis.
Scope and Mechanism of the Pt-Catalyzed Enantioselective Diboration of Monosubstituted Alkenes
作者:John R. Coombs、Fredrik Haeffner、Laura T. Kliman、James P. Morken
DOI:10.1021/ja4041016
日期:2013.7.31
The Pt-catalyzed enantioselective diboration of terminal alkenes can be accomplished in an enantioselective fashion in the presence of chiral phosphonite ligands. Optimal procedures and the substrate scope of this transformation are fully investigated. Reaction progress kinetic analysis and kinetic isotope effects suggest that the stereodefining step in the catalytic cycle is olefin migratory insertion
On the mechanism of osmium catalyzed asymmetric dihydroxylation (ADH) of alkenes
作者:Braj.B. Lohray、Vidya Bhushan
DOI:10.1016/s0040-4039(00)61205-4
日期:1992.8
Dihydroquinidine and dihydroquinine bisesters of malonic acid, adipic acid and terephthalic acids are used as chiral auxiliaries for osmiumtetroxide catalysed asymmetricdihydroxylation of alkenes. Highly stereoselective osmylation of alkenes has been rationalized on the basis of π-π interaction of the alkenes with the ligand.
Kinetic Resolution of 1,2-Diols via NHC-Catalyzed Site-Selective Esterification
作者:Bin Liu、Jiekuan Yan、Ruoyan Huang、Weihong Wang、Zhichao Jin、Giuseppe Zanoni、Pengcheng Zheng、Song Yang、Yonggui Robin Chi
DOI:10.1021/acs.orglett.8b01029
日期:2018.6.15
A kinetic resolution of 1,2-diols bearing both a secondary and a primary alcohol motif through an N-heterocyclic carbene-catalyzed oxidativeacylation reaction has been developed. A site- and enantioselective esterification reaction is involved for this process. Both the monoacylated diols obtained and the remaining enantioenriched 1,2-diols are versatile building blocks for the preparation of functional
We herein report a transition-metal-free cross-coupling between secondaryalkylhalides/mesylates and aryl/alkenylboronic acid, providing expedited access to a series of nonchiral/chiral coupling products in moderate to good yields. Stereospecific SN2-type coupling is developed for the first time with alkenylboronic acids as pure nucleophiles, offering an attractive alternative to the stereospecific
Enantioselective trans-Dihydroxylation of Aryl Olefins by Cascade Biocatalysis with Recombinant <i>Escherichia coli</i> Coexpressing Monooxygenase and Epoxide Hydrolase
作者:Shuke Wu、Yongzheng Chen、Yi Xu、Aitao Li、Qisong Xu、Anton Glieder、Zhi Li
DOI:10.1021/cs400992z
日期:2014.2.7
85–89% for 5 diols; 65% for 1 diol). E. coli (SSP1) and E. coli (SST1) catalyzed the trans-dihydroxylation of trans-aryl olefin 16a and cis-aryl olefin 17a with excellent and complementary stereoselectivity, giving each of the four stereoisomers of 1-phenyl-1,2-propanediol 16c in high ee and de, respectively. Both strains catalyzed the trans-dihydroxylation of aryl cyclic olefins 18a and 19a to afford