Cationic Chiral Fluorinated Oxazaborolidines. More Potent, Second-Generation Catalysts for Highly Enantioselective Cycloaddition Reactions
作者:Karla Mahender Reddy、Eswar Bhimireddy、Barla Thirupathi、Simon Breitler、Shunming Yu、E. J. Corey
DOI:10.1021/jacs.6b00100
日期:2016.2.24
placement of fluorine substituents in the chiral ligand. This approach has led to a new, second-generation family of chiral oxazaborolidinium cationic species which can be used to effect many Diels-Alder reactions in >95% yield and >95% ee usingcatalyst loadings at the 1-2 mol % level. The easy recovery of the chiral ligand makes the application of these new catalysts especially attractive for large-scale
Enantioselective Synthesis of Allylic Alcohols via an Oxazaborolidinium Ion Catalyzed Diels−Alder/Retro-Diels−Alder Sequence
作者:Simon Jones、Damien Valette
DOI:10.1021/ol902280d
日期:2009.11.19
A triflimide-activated oxazaborolidine catalyst successfully promoted the asymmetric Diels−Alder reaction of 9-methylanthracene with methacrolein in high regio- and enantioselectivity. The cycloadduct obtained was subsequently used as a chiral template to access secondary and tertiary allylic alcohols in good to high enantiomeric excess via a cycloreversion by flash vacuum pyrolysis.
Useful Applications of Enantioselective (4 + 2)-Cycloaddition Reactions to the Synthesis of Chiral 1,2-Amino Alcohols, 1,2-Diamines, and β-Amino Acids
作者:Karla Mahender Reddy、Barla Thirupathi、E. J. Corey
DOI:10.1021/acs.orglett.7b02437
日期:2017.9.15
The scope of enantioselective (4 + 2)-cycloaddition reactions has been expanded to include reactive olefinic components that are equivalents of three inoperable and unstable ethylene derivatives: 1-hydroxy-2-aminoethylene, 1,2-diaminoethylene, and β-aminoacrylic acid. In this way, a variety of otherwise unavailable functionalized (4 + 2)-cycloadducts have been synthesized from 1,3-dienes with high
Toward the Stereoselective Synthesis of Arthrobotrisin A: Fragment Synthesis and Coupling Studies
作者:Harshadas Meshram、Rayala Kumar、Nandigama Kumar
DOI:10.1055/s-0036-1588950
日期:——
stereocontrolled synthesis of arthrobotrisin A based on a Nozaki–Hiyama–Kishi (NHK) coupling strategy was developed. Highlights of the fragment synthesis include enzyme-catalyzed kinetic resolution, Negishi carbometalation–iodination, quinone formation through oxidation with hypervalent iodine, chiral oxazaborolidine-catalyzed asymmetric Diels–Alder reaction with cyclopentadiene, regio- and stereoselective epoxidation
A catalytic route toward chiral Morita–Baylis–Hillman esters by asymmetric coupling between α,β‐acetylenic esters, aldehydes, and trimethylsilyl iodide has been developed (see scheme). The reaction proceeds with high to excellent enantioselectivities, and the products can be transformed into β‐branched derivatives in a single step and with excellent retention of configuration. TMS=trimethylsilyl