Diastereocontrol in [4+4]-photocycloadditions of pyran-2-ones: effect of ring substituents and chiral ketal
摘要:
4-Mesyloxypyran-2-ones joined to furan by a three-carbon linker undergo intramolecular-crossed [4+4]-photocycloaddition with high or complete selectivity for the exo cycloadcluct. When a C-2-symmetric ketal was present on the tether adjacent to the pyranone ring, moderate levels of asymmetric induction were obtained. (C) 2009 Elsevier Ltd. All rights reserved.
A mechanistically designed mono-cinchona alkaloid is an excellent catalyst for the enantioselective dihydroxylation of olefins
作者:E.J. Corey、Mark C. Noe、Michael J. Grogan
DOI:10.1016/s0040-4039(00)78237-2
日期:1994.8
advanced regarding the origin of enantioselectivity in the OsO4-promoted dihydroxylation of olefins catalyzed by bis-cinchona alkaloid derivatives such as 1, specifically strong evidence for reaction via transition state assembly 2, the mono-quinidine derivative 3 was selected as a promising catalytic ligand. The experimental observation of high enantioselectivity promoted by 3 provides additional
Synthesis of chiral nonracemic diols via nucleophilic opening of (S,S)-1,2,3,4-diepoxybutane
作者:Paul N. Devine、Taeboem Oh
DOI:10.1016/s0040-4039(00)92111-7
日期:1991.2
(S,S)-1,2,3,4-diepoxybutane was synthesized from (R,R)-dimethyl tartrate. Nucleophilic opening of this diepoxybutane gave a convenient method for generating a variety of chiral nonracemic diols.
Regio- and Stereoselective Reduction of Diketones and Oxidation of Diols by Biocatalytic Hydrogen Transfer
作者:Klaus Edegger、Wolfgang Stampfer、Birgit Seisser、Kurt Faber、Sandra F. Mayer、Reinhold Oehrlein、Andreas Hafner、Wolfgang Kroutil
DOI:10.1002/ejoc.200500839
日期:2006.4
The asymmetric reduction of symmetrical and nonsymmetrical diketones as well as the stereoselectiveoxidation of various diols by biocatalytic hydrogen transfer was investigated by employing lyophilized cells of Rhodococcus ruber DSM 44541 containing alcohol dehydrogense ADH-‘A’. Symmetrical and nonsymmetrical diketones at the (ω-1)- and (ω-2)-positions are reduced to the Prelog product with high stereopreference
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.
Documenting the scope of the catalytic asymmetric dihydroxylation
作者:B. Bhushan Lohray、Thomas H. Kalantar、B. Moon Kim、Christine Y. Park、Tomoyuki Shibata、John S.M. Wai、K. Barry Sharpless
DOI:10.1016/s0040-4039(01)93706-2
日期:1989.1
variety of functionalized and unfunctionalized olefins are efficiently converted to the corresponding cis vicinal diols in moderate to good enantiomeric excess via the “slow addition” enhanced catalyticasymmetric osmylation process.