Efficient Lewis Acid Catalyst Research Articles

CeCl3·7H2O‐catalyzed one‐pot Kabachnik–Fields reaction: A green protocol for three‐component synthesis of α‐aminophosphonates

AbstractCeCl3·7H2O has been utilized as an efficient Lewis acid catalyst for the three‐component coupling of aldehydes, aromatic amines, and diethylphosphite to produce α‐aminophosphonates under solvent‐free conditions. The advantages of this protocol are high yield, mild reaction conditions, less environmental pollution, and simple work‐up procedure. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:397–403, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20635

Ca(CF3COO)2: An efficient Lewis acid catalyst for chemo- and regio-selective enamination of β-dicarbonyl compounds

Abstract A relevant procedure has been developed for the synthesis of β-enaminoesters catalysed by Ca(CF 3 COO) 2 . The reaction of β-ketoesters with primary amines was efficiently carried out under solvent-free conditions at room temperature and led to chemo- and regio-selective formations of enamine derivatives in high yields.

ChemInform Abstract: Metalloporphyrins and Phthalocyanines as Efficient Lewis Acid Catalysts with a Unique Reaction—Field

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

An Efficient Synthesis of New 3,4-Dihydropyrimidin- 2(1H)-ones Incorporating a Phenyl Moiety at C-5 and C-6 Catalyzed by TMSCl and Co(OAc)2.4H2O

New 3,4-dihydropyrimidin-2-ones having a phenyl moiety at C-5 and C-6 have been prepared by a microwave-assisted Biginelli–like reaction by a three-component, one-pot condensation of an aromatic aldehyde, deoxybenzoin and urea, or thiourea using TMSCl and Co(OAc) 2 .4H 2 O as an efficient Lewis acid catalyst.

ChemInform Abstract: Antimony Trioxide as an Efficient Lewis Acid Catalyst for the Synthesis of 5‐Substituted 1H‐Tetrazoles

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Antimony Trioxide as an Efficient Lewis Acid Catalyst for the Synthesis of 5-Substituted 1H-Tetrazoles

Sb2O3 was found to be effective as a catalyst for a smooth (2 + 3) cycloaddition of sodium azide with nitriles to afford 5-substituted 1H-tetrazoles in good yields.

特異な反応場を持つルイス酸触媒としての金属ポルフィリンおよびフタロシアニン錯体

特異な反応場を持つルイス酸触媒としての金属ポルフィリンおよびフタロシアニン錯体

Heterogeneous Lewis Acid Catalysis with Self-Organized Polymeric Rare Earth Arylsulfonates under Solvent-Free Conditions

Polymeric rare earth arylsulfonates, easily prepared from rare earth triisopropoxides and biphenyl-4,4'-disulfonic acid (BPDSA) or 1,3,5-triphenylbenzene trisulfonic acid (TPTSA) in a self-organization manner, were found to work as an efficient heterogeneous Lewis acid catalyst for the hetero-Diels-Alder reaction of aldehydes with the Danishefsky's diene and the ring-opening reaction of epoxides with amines under solvent-free conditions. The catalysts could be quantitatively recovered and reused many times without decreasing their activities.

Highly Regioselective Rearrangement of 2,3-Diaryloxiranes into 2,2-Diarylacetaldehydes Catalyzed by Ytterbium Porphyrin Complex, Yb(TPP)OTf

[5,10,15,20-Tetraphenylporphynato]ytterbium(III) triflate, Yb(TPP)-OTf, is an efficient Lewis acid catalyst for the highly regioselective rearrangement of 2,3-diaryloxiranes into 2,2-diarylacetaldehydes. The catalytic process can be easily performed not only in dichloroethane but also in a more environmentally friendly solvent, benzotrifluoride.

ChemInform Abstract: Polymer‐Supported Gadolinium Triflate as a Convenient and Efficient Lewis Acid Catalyst for Acetylation of Alcohols and Phenols.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Microwave-assisted and Ln(OTf) 3-catalyzed homo-conjugate addition of N-heteroaromatics to activated cyclopropane derivatives

A new expeditious method for the homo-conjugate addition of nitrogen heteroaromatics to 1,1-cyclopropanedicarboxylates was developed in the presence of La(OTf) 3 as an efficient Lewis acid catalyst under microwave irradiation.

Polymer-Supported Gadolinium Triflate as a Lewis Acid Catalyst

Polymer-supported gadolinium triflate (CMPS-IM-Gd) was prepared and found to be an efficient Lewis acid catalyst for the acetylation of various alcohols and phenols with acetic anhydride. Thus, the reaction of Merrifield resin (chloromethyl polystyrene, CMPS) with 1-methyl­imidazole (1.5 equiv) gave CMPS-IM. After the reaction of CMPS-IM with KOt-Bu, the resulting resin was treated with Gd(OTf)3 to afford the CMPS-IM-Gd catalyst. The acetylation of alcohols and phenols with acetic anhydride was carried out in the presence of the CMPS-IM-Gd catalyst (0.5 mol % Gd) to give the corresponding acetylated products in 14 to >99% yield (31 examples).

ChemInform Abstract: A Study of the Diastereoselectivity of Diels—Alder Reactions on the Ce—SiO2 as Support.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Polymer-supported gadolinium triflate as a convenient and efficient Lewis acid catalyst for acetylation of alcohols and phenols

A polymer-supported gadolinium triflate (CMPS-IM-Gd) catalyst was prepared from chloromethyl polystyrene (CMPS) resin using a simple and convenient procedure. This polymeric catalyst was used as an efficient Lewis acid catalyst for the acetylation of various alcohols and phenols with acetic anhydride, affording high yields under mild conditions. The reaction was completed in a short period of time with small amounts of the catalyst. The catalyst was reused over 10 times without any significant loss of its catalytic activity.

A Study of the Diastereoselectivity of Diels-Alder Reactions on the Ce-SiO2as Support

The diastereoselectivity of Diels-Alder reactions were studied on the silica surface supported with different concentrations of cerium ion as efficient Lewis acid catalysts under solvent-free conditions. The results showed that the diastereoselectivity of reaction was highly improved in these conditions. The cerium ion was grafted on silica surface by using ion exchange method.

Diastereoselective Addition of α‐Substituted α‐Amino‐H‐phosphinates to Imines Using Yb(OTf)3 as an Efficient Lewis Acid Catalyst.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Application of Zinc(II)–Binol for the Formal Aza‐Diels–Alder Reaction of N‐Arylimines with Danishefsky's Diene: CD‐Based Absolute Stereochemistry Determination, Origin of Asymmetric Induction and Mechanistic Considerations

AbstractZinc(II)–binol has been employed as an efficient Lewis acid catalyst (10 or 100 mol‐% loading) for the formal aza‐Diels–Alder reaction of ester, furyl and dimethyl acetal‐substituted N‐aryl imines. Asymmetric induction varies from poor to good, with the major enantiomer obtained being (S) when the (S)‐binol complex has been employed. The absolute stereochemistry of the dimethyl acetal‐substituted cycloaduct was determined by CD, and both efficient aza‐Diels–Alder reaction and asymmetric induction are proposed to be dependent upon the formation of bidentate zinc‐imine complexes. These complexes have been modelled using semi‐empirical methods. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Lanthanum trichloride: an efficient Lewis acid catalyst for chemo and regioselective enamination of β-dicarbonyl compounds

The various β-ketocarbonyl compounds rapidly form enaminone derivatives with a variety of amines at room temperature in the presence of a catalytic amount of lanthanum trichloride heptahydrate. The reaction proceeds smoothly at room temperature in methylene dichloride solvent.

Diastereoselective addition of α-substituted α-amino- H-phosphinates to imines using Yb(OTf) 3 as an efficient Lewis acid catalyst

Diastereoselective addition of α-substituted α-amino- H-phosphinates to imines is described. Among Lewis acids, Yb(OTf) 3 was found to be the best catalyst. α,α′-Diaminophosphinic derivatives were obtained with de's ranging from 10 to 95% in the presence of Yb(OTf) 3 as an efficient Lewis acid catalyst. The reaction proceeded with retention of configuration at the phosphorus atom.

Facile protection of carbonyl compounds as oxathiolanes and transoxathioacetalization of oxyacetals promoted by iron(III) trifluoroacetate or trifluoromethanesulfonate as chemoselective and recyclable catalysts

Oxathioacetalization of carbonyl compounds and transoxathioacetalization of O, O-acetals/ketals are reported under nearly neutral conditions promoted by iron(III) trifluoroacetate [Fe(CF 3CO 2) 3] or trifluoromethanesulfonate [Fe(CF 3SO 3) 3] as recyclable and highly efficient Lewis acid catalysts.