نتایج جستجو برای: base catalyst

تعداد نتایج: 299630  

Journal: :Journal of the American Chemical Society 2007
Guosheng Liu Shannon S Stahl

A number of different PdII catalyst systems have been reported recently for the Wacker-type aerobic oxidative cyclization of alkenes bearing tethered nitrogen nucleophiles. This study examines the stereochemistry of the aminopalladation step with five different catalyst systems: Pd(OAc)2/DMSO (A), PdX2/pyridine [X = OAc (B), O2CCF3 (C)], Pd(IMes)(O2CCF3)2(OH2) (D), and Pd(O2CCF3)2/(-)-sparteine...

2015
Rafique Ul Islam Abu Taher Meenakshi Choudhary Samarjeet Siwal Kaushik Mallick

During the polymerization of aniline using copper sulphate, act as an oxidizing agent, the in-situ synthesized Cu(I) ion catalyzed the cyclo-addition between azides and alkynes. This work represents the merging of two steps, synthesis of the catalyst and application of the catalyst, in a one pot reaction. The elimination of the separate catalyst synthesis step is economic in terms of cost and t...

Journal: :Organic & biomolecular chemistry 2006
Roberto Ceccarelli Susanna Insogna Marco Bella

Cyclohexanone and cycloheptanone can be enantioselectively functionalized in the 3-position with up to 92% ee and 87% ee, respectively, by the base-promoted dimerization of the corresponding enones using 3,4,5-tribenzyloxybenzyl cinchoninium bromide, as a new effective catalyst.

Journal: :Organic & biomolecular chemistry 2014
Cunxiang Su Ying Xie Hongjie Pan Mao Liu Hua Tian Yian Shi

This paper describes an efficient asymmetric biomimetic transamination of α-keto esters with a quinine-derived chiral base as the catalyst, giving a variety of β-branched α-amino esters in 50-96% yield and 87-95% ee.

Journal: :Chemical communications 2002
Stewart A Forsyth Douglas R MacFarlane Robin J Thomson Mark von Itzstein

Archetypal O-acetylation reactions of alcohols and carbohydrates proceed rapidly in high yield under mild conditions in a dicyanamide based ionic liquid, that is not only an effective solvent but also an active base catalyst.

Journal: :Chemical communications 2009
Yong-Chua Teo Fui-Fong Yong Chai-Yun Poh Yaw-Kai Yan Guan-Leong Chua

A facile and convenient strategy for the assembly of N-arylated heterocycles has been demonstrated using a MnCl2.4H2O/trans-1,2-diaminocyclohexane catalyst and K3PO4 as the base in water.

Journal: :Chemical communications 2013
Lauren Myles Nicholas Gathergood Stephen J Connon

The ability of triazolium salts to serve as a precatalyst for both an acid and a powerful base/nucleophile (controlled by additives) has been exploited in a process characterised by a unique in situ catalyst modification strategy.

Journal: :Chemical communications 2009
Jia Wang Yan-Liang Liang Jin Qu

A general protocol for removing Boc groups from various types of nitrogen is reported and a preliminary investigation of the reaction mechanism indicates that water acts as a dual acid/base catalyst at elevated temperature.

Journal: :Organic & biomolecular chemistry 2012
Seiji Shirakawa Kensuke Ota Shogo J Terao Keiji Maruoka

Enantioselective direct aldol reaction of α-substituted nitroacetates with aqueous formaldehyde for the synthesis of α-alkyl serines has been achieved under base-free neutral phase-transfer conditions with a bifunctional chiral phase-transfer catalyst.

Journal: :Organic & biomolecular chemistry 2010
Fuchun Xie Xuan Pan Shijun Lin Youhong Hu

A novel base-promoted cascade desalicyloylative dimerization of 3-(1-alkynyl)chromones to produce 2-alkynyl xanthones has been developed. This tandem process involves multiple reactions, such as Michael additions/cyclizations/desalicyloylation without a transition metal catalyst and inert atmosphere.

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