The Experts below are selected from a list of 38877 Experts worldwide ranked by ideXlab platform
Shuai Zhao - One of the best experts on this subject based on the ideXlab platform.
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catalyst free chemoselective synthesis of 3 4 dihydroquinazoline 2 thiones and 2 imino 1 3 benzothiazines
Journal of Organic Chemistry, 2016Co-Authors: Ting Xie, Yu Xiao, Shuai ZhaoAbstract:A solvent-controlled catalyst-free chemoselective reaction was developed. Both 3,4-dihydroquinazoline-2-thiones and 2-imino[1,3]benzothiazines could be efficiently constructed by the reaction of 2-amino chalcones with isothiocyanates via two different chemoselective reactions depending on the solvents. The reaction was modulated by the solvents to proceed via either Aza-Michael Addition or thia-Michael Addition as the major reaction with excellent yields.
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Catalyst-Free Chemoselective Synthesis of 3,4-Dihydroquinazoline-2-thiones and 2‑Imino[1,3]benzothiazines
2016Co-Authors: Ting Xie, Yu Xiao, Shuai ZhaoAbstract:A solvent-controlled catalyst-free chemoselective reaction was developed. Both 3,4-dihydroquinazoline-2-thiones and 2-imino[1,3]benzothiazines could be efficiently constructed by the reaction of 2-amino chalcones with isothiocyanates via two different chemoselective reactions depending on the solvents. The reaction was modulated by the solvents to proceed via either Aza-Michael Addition or thia-Michael Addition as the major reaction with excellent yields
Shuanghua Cheng - One of the best experts on this subject based on the ideXlab platform.
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enantioselective synthesis of 3 substituted 1 2 oxazinanes via organocatalytic intramolecular aza michael Addition
ChemInform, 2015Co-Authors: Shuanghua ChengAbstract:A variety of 3-substituted 1,2-oxazinanes (II) is obtained by quinine-catalyzed intramolecular Aza-Michael reaction of enones (I) with moderate to high enantioselectivity.
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enantioselective synthesis of 3 substituted 1 2 oxazinanes via organocatalytic intramolecular aza michael Addition
Organic and Biomolecular Chemistry, 2014Co-Authors: Shuanghua ChengAbstract:A highly enantioselective intramolecular 6-exo-trig Aza-Michael Addition was developed to afford chiral 3-substituted 1,2-oxazinanes in high yields (up to 99% yield) and good enantioselectivities (up to 98/2 er). These reactions were enabled by a quinine-derived primary–tertiary diamine as a catalyst and pentafluoropropionic acid (PFP) as a co-catalyst.
Chorngshyan Chern - One of the best experts on this subject based on the ideXlab platform.
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kinetics and mechanisms of non isothermal polymerization of n n bismaleimide 4 4 diphenylmethane with cyanuric acid
Thermochimica Acta, 2021Co-Authors: Quocthai Pham, Anh Ngoc Tram Mai, Chorngshyan ChernAbstract:Abstract Mechanisms and kinetics of non-isothermal polymerization of N,N′-bismaleimide-4,4′-diphenylmethane (BMI) with cyanuric acid (CA) were investigated. Competitive free radical polymerization and Aza-Michael Addition reaction mechanisms involved in the BMI/CA reaction system were characterized by using DSC, 1H-NMR, electron spin resonance (ESR) and gel permeation chromatography (GPC). Free radical polymerization mechanism predominated in the BMI/CA reaction system. Both model-free and model-fitting methods were used to determine the isoconversional activation energy (Eα) and pre-exponential factor (Aα). The values of Eα and Aα for Aza-Michael Addition reaction evaluated at α = 0.1 were 86 kJ mol-1 and 2.42 × 1010 min-1, respectively, and the reaction model was f(α) = 1.73(1 - α)α0.11. By contrast, Eα gradually decreased with increasing α (decreased from 88 to 48 kJ mol-1) in the α range 0.15-0.9, which was attributed to the inherent multi-step kinetics in free radical polymerization.
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mechanisms and kinetics of isothermal polymerization of n n bismaleimide 4 4 diphenylmethane with 5 5 dimethylbarbituric acid in the presence of triphenylphosphine
Thermochimica Acta, 2017Co-Authors: Quocthai Pham, Jungmu Hsu, Wanju Shao, Fuming Wang, Chorngshyan ChernAbstract:Abstract Mechanisms and kinetics of isothermal polymerization of N,N′ -bismaleimide-4,4′-diphenylmethane (BMI) with 5,5-dimethylbarbituric acid (55BTA) in the presence of triphenylphosphine (Ph 3 P, as a base catalyst for Aza-Michael Addition reaction) were investigated. Both model-free and model-fitting methods were used to determine triplet kinetic parameters, and comparable kinetic parameters obtained. Based on the model-free method, average activation energy (E α ) and pre-exponential factor (A α ) are 33 ± 1 kJ mol −1 and 8267 ± 2 min −1 in the α range 0.1–0.9, respectively, with g(α) = [(1 − α) −0.1 − 1]/0.1 [i.e. f(α) = (1 − α) 1.1 ]. As to the model-free method, overall activation energy (E) and pre-exponential (A) are 32 ± 1 kJ mol −1 and 4583 ± 1 min −1 with the g(α) = [(1 − α) −0.1 − 1]/0.1. Aza-Michael Addition reaction mechanism played an important role in the polymerization of BMI/55BTA in the presence of Ph 3 P at low temperature. By contrast, free radical polymerization predominated in the BMI/55BTA system at higher temperature.
Ting Xie - One of the best experts on this subject based on the ideXlab platform.
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catalyst free chemoselective synthesis of 3 4 dihydroquinazoline 2 thiones and 2 imino 1 3 benzothiazines
Journal of Organic Chemistry, 2016Co-Authors: Ting Xie, Yu Xiao, Shuai ZhaoAbstract:A solvent-controlled catalyst-free chemoselective reaction was developed. Both 3,4-dihydroquinazoline-2-thiones and 2-imino[1,3]benzothiazines could be efficiently constructed by the reaction of 2-amino chalcones with isothiocyanates via two different chemoselective reactions depending on the solvents. The reaction was modulated by the solvents to proceed via either Aza-Michael Addition or thia-Michael Addition as the major reaction with excellent yields.
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Catalyst-Free Chemoselective Synthesis of 3,4-Dihydroquinazoline-2-thiones and 2‑Imino[1,3]benzothiazines
2016Co-Authors: Ting Xie, Yu Xiao, Shuai ZhaoAbstract:A solvent-controlled catalyst-free chemoselective reaction was developed. Both 3,4-dihydroquinazoline-2-thiones and 2-imino[1,3]benzothiazines could be efficiently constructed by the reaction of 2-amino chalcones with isothiocyanates via two different chemoselective reactions depending on the solvents. The reaction was modulated by the solvents to proceed via either Aza-Michael Addition or thia-Michael Addition as the major reaction with excellent yields
Takahiko Akiyama - One of the best experts on this subject based on the ideXlab platform.
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chiral phosphoric acid catalyzed asymmetric synthesis of 2 substituted 2 3 dihydro 4 quinolones by a protecting group free approach
Organic Letters, 2015Co-Authors: Kodai Saito, Yuka Moriya, Takahiko AkiyamaAbstract:Chiral 2-substituted 2,3-dihydro-4-quinolones were synthesized based on the chiral phosphoric acid catalyzed intramolecular Aza-Michael Addition reaction using N-unprotected 2-aminophenyl vinyl ketones as substrates in good yields with high enantioselectivities.
