نتایج جستجو برای: organocatalyst

تعداد نتایج: 407  

2012
Tatyana E Shubina Matthias Freund Sebastian Schenker Timothy Clark Svetlana B Tsogoeva

A new guanidine-thiourea organocatalyst has been developed and applied as bifunctional organocatalyst in the Michael addition reaction of diethyl malonate to trans-β-nitrostyrene. Extensive DFT calculations, including solvent effects and dispersion corrections, as well as ab initio calculations provide a plausible description of the reaction mechanism.

Journal: :Chemical communications 2013
Shinji Kitagaki Takahiro Ueda Chisato Mukai

A bis(thiourea) organocatalyst with a planar chiral [2.2]paracyclophane backbone has been synthesized and applied to the Henry reaction. The obtained high reactivity and enantioselectivity from the reaction of aromatic aldehydes with nitroalkanes suggested the significant potential of [2.2]paracyclophane to serve as the backbone of the organocatalyst.

Journal: :Chemical communications 2011
Tamal K Sen Samaresh Ch Sau Arup Mukherjee Arghya Modak Swadhin K Mandal Debasis Koley

The recently isolated abnormal N-heterocyclic carbene (aNHC) has been established as an efficient organocatalyst in ring opening polymerization of three different cyclic esters rac-lactide (rac-LA), ε-caprolactone (ε-CL), and δ-valerolactone (δ-VL). Preliminary DFT calculations indicate that aNHC can be a better organocatalyst than the corresponding nNHC counterpart.

Journal: :Chemical communications 2016
Jaime Fernández-Casado Ronald Nelson José L Mascareñas Fernando López

Aldehydes can be α-alkylated with allenamides by the combined action of an organocatalyst and a gold complex. The reaction requires the simultaneous generation of an enamine and a gold-activated allenamide. Importantly, by using a chiral amine as organocatalyst it is possible to obtain aldehyde products featuring all-carbon quaternary stereocenter at their α-position, with moderate to good leve...

Journal: :Organic & biomolecular chemistry 2012
Tsuyoshi Miura Hikaru Kasuga Kie Imai Mariko Ina Norihiro Tada Nobuyuki Imai Akichika Itoh

A fluorous organocatalyst promotes direct asymmetric aldol reactions of aromatic aldehydes with ketones in brine to afford the corresponding anti-aldol products in high yield with up to 96% ee. Fluorous organocatalyst can be readily recovered by solid phase extraction using fluorous silica gel and reused without purification.

Journal: :Organic & biomolecular chemistry 2012
Derek R Boyd Mark Bell Katherine S Dunne Brian Kelly Paul J Stevenson John F Malone Christopher C R Allen

The chemoenzymatic synthesis of a Lewis basic phosphine-phosphine oxide organocatalyst from a cis-dihydrodiol metabolite of bromobenzene proceeds via a palladium-catalysed carbon-phosphorus bond coupling and a novel room temperature Arbuzov [2,3]-sigmatropic rearrangement of an allylic diphenylphosphinite. Allylation of aromatic aldehydes were catalysed by the Lewis basic organocatalyst giving ...

Journal: :Journal of the American Chemical Society 2011
Bin Tan Gloria Hernández-Torres Carlos F Barbas

Carbazolespirooxindole derivatives were synthesized in a high-yielding, atypically rapid, stereocontrolled Diels-Alder reaction catalyzed by a C(2)-symmetric bisthiourea organocatalyst. Simple precursors and mild conditions were used to construct carbazolespirooxindole derivatives with high enantiopurity and structural diversity under H-bonding catalysis. The practical approach recycles the org...

Journal: :Chemical & pharmaceutical bulletin 2016
Takeshi Yamada Koh Suzuki Tomoyasu Hirose Takumi Furuta Yoshihiro Ueda Takeo Kawabata Satoshi Ōmura Toshiaki Sunazuka

The organocatalytic site-selective monoacylation of avermectin B2a, an insecticidal and anti-parasitic drug, was accomplished. Although an acetylation of avermectin B2a using a 4-dimethylaminopyridine (DMAP) as a catalyst gave poor site-selectivity, use of our organocatalyst increased site-selectivity of the acylation at the C-5-OH as well as the yield of monoacetate. This catalyst was also eff...

Journal: :Nature communications 2014
Kayambu Namitharan Tingshun Zhu Jiajia Cheng Pengcheng Zheng Xiangyang Li Song Yang Bao-An Song Yonggui Robin Chi

Transition metal and organic catalysts have established their own domains of excellence. It has been expected that merging the two unique domains should provide complimentary or unprecedented opportunities in converting simple raw materials to functional products. N-heterocyclic carbenes alone are excellent organocatalysts. When used with transition metals such as copper, N-heterocyclic carbene...

Journal: :ChemistrySelect 2022

A new proline analogue with the camphor-based 1,3-diamine unit is presented. This readily available from chiral pool providing a organocatalyst one free primary amine group next to secondary of unit. The diamine fragment had significant effect on catalytic activity organocatalyst.

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