Metal-free ring expansion of indoles with nitroalkenes: a simple, modular approach to 3-substituted 2-quinolones
作者:Alexander V. Aksenov、Alexander N. Smirnov、Nicolai A. Aksenov、Inna V. Aksenova、Jonathon P. Matheny、Michael Rubin
DOI:10.1039/c4ra14406f
日期:——
3-Substituted 2-quinolones are obtained via a novel metal-free transannulation reaction of 2-nitroolefins with 2-substitutedindoles in polyphosphoric acid. This acid-mediated cascade transformation operates via the ANRORC (Addition of Nucleophile, Ring Opening, and Ring Closure) mechanism and can be used in combination with the Fisher indole synthesis to offer a practical three-component hetero-annulation
Organocatalytic asymmetric Michael/hemiacetalization/acyl transfer reaction of α-nitroketones with <i>o</i>-hydroxycinnamaldehydes: synthesis of 2,4-disubstituted chromans
作者:Rajendra Maity、Subhas Chandra Pan
DOI:10.1039/c8ob00078f
日期:——
An organocatalyticasymmetriccascadeMichael/hemiketalization/acyl transfer reaction between o-hydroxycinnamaldehydes and α-nitroketones is developed. Prolinol TMS ether catalyst in combination with benzoic acid was found to be the most effective for this reaction which proceeds through an equilibrium of lactols to provide a single diastereomer of enantiopure 2,4-disubstituted chromans.
α-Nitro-α,β-Unsaturated Ketones: An Electrophilic Acyl Transfer Reagent in Catalytic Asymmetric Friedel–Crafts and Michael Reactions
作者:Chandrakanta Parida、Rajendra Maity、Subas Chandra Sahoo、Subhas Chandra Pan
DOI:10.1021/acs.orglett.9b02310
日期:2019.9.6
α-nitro-α,β-unsaturated ketones as efficient electrophilic acyl transfer reagents, and they were employed in Friedel-Crafts as well as in Michael reactions. The desired acyl transfer products of these reactions were obtained in high yields with high to excellent enantioselectivities with t-leucine-derived squaramide catalyst under mild reaction conditions. Few applications including a synthesis of the isoxazoline
Organocatalytic Asymmetric Domino Michael/Acyl Transfer Reaction Between <i>α</i>
-Nitroketones and <i>in situ-</i>
Generated <i>ortho</i>
-Quinone Methides: Route to 2-(1-Arylethyl)phenols
作者:Chandan Gharui、Debasmita Behera、Subhas Chandra Pan
DOI:10.1002/adsc.201801015
日期:2018.12.3
organocatalytic asymmetric domino Michael/acyl transfer reaction between α‐nitroketones and o‐quinone methides is disclosed. o‐Quinone methides are generated in situ from 2‐sulfonylmethylphenols in basic medium. With 10 mol% of bifunctional squaramide catalyst, high yields and excellent enantioselectivities are achieved for a variety of O‐acyl 2‐(1‐arylethyl)phenols under mild reaction condition.