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.
Organocatalytic Asymmetric Michael/Hemiketalization/Retro-aldol Reaction of α-Nitroketones with Unsaturated Pyrazolones: Synthesis of 3-Acyloxy Pyrazoles
作者:Rajendra Maity、Chandan Gharui、Arun K. Sil、Subhas Chandra Pan
DOI:10.1021/acs.orglett.6b03823
日期:2017.2.3
An organocatalyticasymmetriccascadeMichael/hemiketalization/retro-aldol reaction between unsaturated pyrazolones and α-nitroketones is described. A bifunctional thiourea catalyst was found to be efficient for this reaction. With 10 mol % of catalyst, high yields as well as excellent enantioselectivities are attained for a variety of 3-acyloxy pyrazoles under mild reaction conditions.
Catalytic Enantioselective Synthesis of 3,4,5-Trisubstituted Isoxazoline <i>N</i>
-Oxides and Regioselective Synthesis of 3,4,5-Trisubstituted Isoxazoles
作者:Subas Chandra Sahoo、Subhas Chandra Pan
DOI:10.1002/ejoc.201801693
日期:2019.2.14
A convenient catalytic asymmetric synthesis of 3,4,5‐trisubstituted isoxazoline N‐oxides and regioselective synthesis of 3,4,5‐trisubstitutedisoxazoles has been developed.
Organocatalytic Asymmetric Michael-Acyl Transfer Reaction of α-Nitroketones with 2-Hydroxybenzylidene Ketones
作者:Rajendra Maity、Subas Chandra Sahoo、Subas Chandra Pan
DOI:10.1002/ejoc.201900069
日期:2019.3.31
This paper depicts primary amine catalyzed asymmetric cascade Michael–acyl transfer reaction of α‐nitroketones and 2‐hydroxybenzylidene ketones. The desired products having nitro, keto, and ester functionalities were obtained in high yields with excellent enantioselectivities under mild reaction conditions.
Organocatalytic Asymmetric Domino Michael/Acyl Transfer Reaction between γ/δ-Hydroxyenones and α-Nitroketones
作者:Keshab Mondal、Subhas Chandra Pan
DOI:10.1021/acs.joc.8b00436
日期:2018.5.4
An organocatalyticasymmetric domino Michael/acyl transfer reaction has been developed between γ/δ-hydroxyenones and α-nitroketones. Cinchona alkaloid derived bifunctional amino-squaramide catalysts were found to be the best catalysts for this reaction. The products having nitro, keto, and ester functionalities were obtained in high yields and with excellent enantioselectivities, and also a few synthetic