نتایج جستجو برای: lewis acid catalyst

تعداد نتایج: 798753  

Journal: :Chemical communications 2009
Kohji Suda Shin-Ichiro Nakajima Yasumi Satoh Toshikatsu Takanami

The metallophthalocyanine complex Cr(TBPC)OTf works as a highly efficient, recyclable Lewis acid catalyst for the regio- and stereoselective rearrangements of epoxides to aldehydes.

Journal: :Organic chemistry frontiers 2021

Piancatelli rearrangement on substituted non-symmetrical furan-2,5-dicarbinols has been developed using an effective combination of microwave activation and Lewis acid catalyst.

Journal: :The Journal of organic chemistry 2013
Hu Chen Zhaofeng Wang Yingnan Zhang Yong Huang

A triple cascade was developed using a simple copper catalyst to trans-selectively access bicyclic isoxazolidines in a one-pot synthesis. This strategy features the in situ generation of nitrones and subsequent trapping by [3 + 2] cycloaddition. In this method, copper serves three catalytic functions: as a Lewis acid for the ene reaction, as an organometallic for aerobic oxidation, and as a Lew...

2006
Masakatsu Shibasaki

Asymmetric catalysis is a powerful component of modern synthetic organic chemistry. To further broaden the scope and utility of asymmetric catalysis, new basic concepts for the design of asymmetric catalysts are crucial. Because most chemical reactions involve bond-formation between two substrates or moieties, high enantioselectivity and catalyst activity should be realized if an asymmetric cat...

2016
Huanfeng Jiao Xiaoliang Zhao Chunxiao Lv Yijun Wang Dongjiang Yang Zhenhuan Li Xiangdong Yao

One-dimensional γ-Al2O3 nanofibers were modified with Nb2O5 to be used as an efficient heterogeneous catalyst to catalyze biomass into 5-hydroxymethylfurfural (5-HMF). At low Nb2O5 loading, the niobia species were well dispersed on γ-Al2O3 nanofiber through Nb-O-Al bridge bonds. The interaction between Nb2O5 precursor and γ-Al2O3 nanofiber results in the niobia species with strong Lewis acid si...

Journal: :The Journal of organic chemistry 2003
Ahmed M Hafez Travis Dudding Ty R Wagerle Meha H Shah Andrew E Taggi Thomas Lectka

A catalytic asymmetric procedure for the preparation of beta-amino acids (specifically beta-substituted aspartic acid derivatives) is reported. The cinchona alkaloid catalyst benzoylquinine (BQ) mediates up to five distinct steps of a reaction pathway, all in one reaction vessel. The products of this reaction, highly optically enriched beta-substituted aspartic acid derivatives, were prepared f...

2014
VIPIN KUMAR

Heterogeneous catalysis and their application in industrial-scale organic synthesis of fine chemicals are greatly facilitated by catalysis and further on by catalyst recovery and recycles to fits most “principles of green chemistry. In acid media, terpenoids generally undergoes various transformations. The terpenoid transformations include various liquid Bronsted and Lewis Acids, Acid clays, He...

Journal: :The journal of physical chemistry. A 2005
Qingbin Li Ken C Hunter Allan L L East

Cracking of an all-trans n-alkane, via idealized Lewis acid and Bronsted acid catalysis, was examined using density functional theory. Optimized geometries and transitions states were determined for catalyst-reactant complexes, using AlCl3 and HCl.AlCl3 as the Lewis and Bronsted acids. For the Lewis acid cycle, hydride-transfer steps are seen to have large barriers in both forward and reverse d...

Dadkhoda Ghazanfari, Enayatollah Sheikhhosseini, Mahdieh Yahyazadehfar Sayed Ali Ahmadi

Known as a Lewis acid which acts as a natural catalyst, bentonite can be used to produce several arylidene  (thio) barbituric  acid  derivatives  through  conducting  a  Knoevenagel  reaction  between aromatic aldehydes and (thio) barbituric acid. Water is considered as the medium for this reaction and the results are at arange of good to excellent over a reasonable reaction time. This method i...

Journal: :Chemical communications 2013
Wenchao Chen Wenguo Yang Lin Yan Choon-Hong Tan Zhiyong Jiang

Highly enantioselective phase-transfer alkylation of 3-substituted-2-oxindoles with activated bromomethanes is disclosed with a broad substrate scope by using bicyclic guanidinium as a catalyst and a Lewis acid as the co-catalyst. The alkylation adducts are versatile intermediates to accomplish the syntheses of pyrroloindolines and furoindolines.

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