Results 121 to 130 of about 16,879 (311)

A C3‐symmetric Diphenylethylendiamine‐Based Catalyst in the Asymmetric Michael Addition of α,β‐Unsaturated Ketones with 4‐Hydroxycoumarin and 4‐Hydroxyquinolin‐2‐one

European Journal of Organic Chemistry, Accepted Article.
Even though the amino‐organo catalysis has been known for decades, the use of chiral C3‐symmetric multi–amino catalysts in asymmetric synthesis is not widespread. Herein, we extended the approach previously employed for the chiral 1,2‐diamino‐cyclohexane to the enantiopure 1,2‐diphenylethylendiammine.
Alessia CIOGLI, Shilashi Badasa Oljira, Martina De Angelis, Simone Manetto, Francesco Fiorentino, Dante Rotili, Luciana Mosca, Daniel Di Risola, Roberto Mattioli, Marco Pierini, Giulia Mazzoccanti   +10 more
wiley   +1 more source

A One-Pot Tandem Strategy in Catalytic Asymmetric Vinylogous Aldol Reaction of Homoallylic Alcohols

Molecules, 2016
Reported is a rationally-designed one-pot sequential strategy that allows homoallylic alcohols to be employed in a catalytic, asymmetric, direct vinylogous aldol reaction with a series of activated acyclic ketones, including trifluoromethyl ketones, γ ...
Xufeng Hou, Zhenzhong Jing, Xiangbin Bai, Zhiyong Jiang   +3 more
doaj   +1 more source

Para-quinone methide: A new player in asymmetric catalysis [PDF]

, 2015
This is the accepted version of the following article: Parra, A. and Tortosa, M. (2015), para-Quinone Methide: a New Player in Asymmetric Catalysis.
Parra, Alejandro, Tortosa Manzanares, Mariola   +1 more
core   +2 more sources

Decarboxylative Michael Additions of Substituted Malonic Acid Half‐Oxyesters to Methylidene Malonates

European Journal of Organic Chemistry, EarlyView.
Substituted malonic acid half oxyesters reacted with alkylidene malonates in a fast, efficient decarboxylative Michael addition, delivering adducts in high yields. The reaction occurred in bulk solvent, open to air, needing only a weak amine base as an organocatalyst to drive a mechanism involving addition prior to decarboxylation.
Marine Pinaud, Tania Xavier, Léa Lin, Erwan Le Gall, Marc Presset   +4 more
wiley   +1 more source

“Dial Up and Lock In”: Asymmetric organo-Brønsted acid catalysis incorporating stable isotopes [PDF]

, 2016
An operationally simple organo-Brønsted-acid-catalyzed asymmetric and regioselective “dial up and lock in” of one or more stable isotopes into organic compounds is unknown.
Bachera, Dominika U., Bew, Sean P., Coles, Simon J., Hiatt-Gipson, Glyn D., Pesce, Paolo, Pitak, Mateusz, Thurston, Sean M., Zdorichenko, Victor   +7 more
core   +1 more source

Enantioselective Desymmetrization of Bisphenol Derivatives by Organocatalytic Sulfonylation

European Journal of Organic Chemistry, EarlyView.
An efficient organocatalytic strategy involving the desymmetrization–sulfonylation of bisphenols is introduced for the synthesis of chiral 1,1‐diarylalkanes. A chiral thiourea catalyst enables the selective sulfonylation of one hydroxyl group with a sulfonyl chloride in a CHCl3/H2O system under basic conditions, affording the reaction products with ...
Judit Hostalet‐Romero, Jaume Rostoll‐Berenguer, Alba Martínez‐Rausell, Daniel Marcilla, Gonzalo Blay, José R. Pedro, Carlos Vila   +6 more
wiley   +1 more source

Poly(ethylene glycol)-supported ααα-trifluoroacetophenone in dioxirane mediated alkene epoxidation reactions [PDF]

, 2004
Poly(ethylene glycol) (PEG) was used for the immobilization of ααα-trifluoroacetophenone and the utility of this supported ketone has been examined in dioxirane mediated epoxidation of alkenes.
Kan, JTW, Toy, P
core   +1 more source

Organocatalytic Enantioselective Synthesis of Oxindole‐4‐Aminopyrazolone Derivatives via Mannich Reaction of 3‐Substituted Oxindoles With Pyrazolinone Ketimines

Journal of Heterocyclic Chemistry, EarlyView.
Hydroquinine‐derived squaramide catalyzes the diastereo‐ and enantioselective Mannich reaction of pyrazolinone ketimines and 3‐aryl‐substituted oxindoles to access oxindole‐4‐aminopyrazolones with vicinal tetrasubstituted stereocenters. ABSTRACT The organocatalyzed Mannich reaction between pyrazolinone ketimines and 3‐aryl‐substituted oxindoles ...
María E. Molinero, Sandra Tejedor, Laura Martín, Alicia Maestro, José M. Andrés   +4 more
wiley   +1 more source

A quantitative approach to nucleophilic organocatalysis

Beilstein Journal of Organic Chemistry, 2012
The key steps in most organocatalytic cyclizations are the reactions of electrophiles with nucleophiles. Their rates can be calculated by the linear free-energy relationship log k(20 °C) = sN(E + N), where electrophiles are characterized by one parameter
Herbert Mayr, Sami Lakhdar, Biplab Maji, Armin R. Ofial   +3 more
doaj   +1 more source

Asymmetric Organocatalysis of [4 + 2] Cycloaddition Reactions. [PDF]

, 2003
Michael Harmata, Sunil K. Ghosh, Xuechuan Hong, Sumrit Wacharasindhu, Patrick L. Kirchhoefer   +4 more
openalex   +1 more source