نتایج جستجو برای: organocatalyst

تعداد نتایج: 407  

Journal: :Molecules 2013
Kankan Zhang Xueping Liang Ming He Jian Wu Yuping Zhang Wei Xue Linhong Jin Song Yang Deyu Hu

An efficient one-pot synthesis of novel β-amino acid derivatives containing a thiadiazole moiety was developed using a chiral squaramide cinchona alkaloid as organocatalyst. The reactions afforded chiral β-amino acid derivatives in moderate yields and with moderate to excellent enantioselectivities. The present study demonstrated for the first time the use of a Mannich reaction catalyzed by a ch...

Journal: :Chirality 2011
Long Qin Lei Li Lei Yi Chao-Shan Da Yi-Feng Zhou

Nitroso compounds have two reactive nitrogen and oxygen atoms. It is interesting and important to perform a nitrogen or oxygen selective reaction with interesting substrates. These atom specific reactions are crucial to specifically synthesis of specific compounds. An enantioselective N-specific reaction of nitrosobenzene with unmodified aldehydes was successfully achieved catalyzed first by a ...

Journal: :Organic & biomolecular chemistry 2015
Lei Wang Zhen Chen Manyuan Ma Wenzeng Duan Chun Song Yudao Ma

An enantioselective conjugate addition of boron to α,β-unsaturated ketones catalysed by either a N-heterocyclic carbene or a copper-carbene complex generated in situ from a new chiral bicyclic triazolium based on [2.2]paracyclophane is presented. The dual chiral carbene-copper catalyst has significant advantages over its carbene counterpart as an organocatalyst in asymmetric β-boration of acycl...

Journal: :Organic letters 2006
Taichi Kano Youhei Tanaka Keiji Maruoka

An organocatalyst formed from a binaphthyl-substituted diamine and trifluoromethanesulfonic acid exhibited unprecedented levels of exo selectivity in the Diels-Alder reaction of alpha,beta-unsaturated aldehydes with cyclopentadiene. A novel axially chiral diamine was also designed as an organocatalyst for an asymmetric variant of this reaction, in which the desired cycloadducts were formed with...

Journal: :Chemical communications 2007
Barbara Procuranti Stephen J Connon

A new class of bifunctional organocatalyst promotes the chemoselective reduction of diketone electrophiles at catalytic loadings in the presence of an inorganic co-reductant.

Journal: :Molecules 2013
Kosuke Nakashima Miho Murahashi Hiroki Yuasa Mariko Ina Norihiro Tada Akichika Itoh Shin-ichi Hirashima Yuji Koseki Tsuyoshi Miura

Asymmetric conjugate additions of branched aldehydes to vinyl sulfones promoted by sulfonamide organocatalyst 6 or 7 have been developed, allowing facile synthesis of the corresponding adducts with all-carbon quaternary stereocenters in excellent yields with up to 95% ee.

Journal: :Chemical communications 2006
Sanzhong Luo Xueling Mi Song Liu Hui Xu Jin-Pei Cheng

A surfactant-type asymmetric organocatalyst (STAO) catalyzed highly efficient Michael addition to nitroalkenes with high stereoselectivities in water without using any organic solvents or additional additives.

Journal: :Chemical communications 2010
Marta Feroci Isabella Chiarotto Monica Orsini Achille Inesi

Electrogenerated N-heterocyclic carbene can behave as an organocatalyst in the Staudinger reaction (from imine and acyl chloride) in a very polar solvent, such as an ionic liquid.

Journal: :Organic & biomolecular chemistry 2011
Qiang Kang Yugen Zhang

Aza-Michael addition of amines, including aromatic and aliphatic amines, with α, β-unsaturated ketones was realized employing N-Heterocyclic Carbene (NHC) as organocatalyst, yielding β-amino ketones with up to 98% yield.

Journal: :Organic & biomolecular chemistry 2013
Utpal Das Yi-Ling Tsai Wenwei Lin

An organocatalytic asymmetric synthesis of spironitrocyclopropanes has been demonstrated starting from 2-arylidene-1,3-indandiones and bromonitroalkanes catalyzed by a cinchona-derived bifunctional organocatalyst. The products were obtained with excellent enantioselectivities, diastereoselectivities and with good yields.

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