Aldol Condensation Of Ketones Research Articles

RuHCl(CO)(PPh3)3-Catalyzed α-Alkylation of Ketones with Primary Alcohols

The α-alkylation reaction of ketones with primary alcohols to give α-alkylated ketones was achieved using RuHCl(CO)(PPh(3))(3) as a catalyst in the presence of Cs(2)CO(3) as a base. This reaction proceeds via an aldol condensation of ketones with aldehydes, formed via transfer dehydrogenation of alcohols, to give α,β-unsaturated ketones, which then undergo transfer hydrogenation with primary alcohols to give α-alkylated ketones and aldehydes, the latter of which participate in the next catalytic cycle. While the reaction of aliphatic primary alcohols was sluggish compared with that of benzylic alcohols, a catalytic amount of 1,10-phenanthroline was found to promote the alkylation dramatically.

ChemInform Abstract: Catalyst‐Free Aldol Condensation of Ketones and Isatins under Mild Reaction Conditions in DMF with Molecular Sieves 4 Å as Additive.

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Catalytic conversion of biomass to biofuels

Biomass has received considerable attention as a sustainable feedstock that can replace diminishing fossil fuels for the production of energy, especially for the transportation sector. The overall strategy in the production of hydrocarbon fuels from biomass is (i) to reduce the substantial oxygen content of the parent feedstock to improve energy density and (ii) to create C–C bonds between biomass-derived intermediates to increase the molecular weight of the final hydrocarbon product. We begin this review with a brief overview of first-generation biofuels, specifically bioethanol and biodiesel. We consider the implications of utilizing starchy and triglyceride feedstocks from traditional food crops, and we provide an overview of second-generation technologies to process the major constituents of more abundant lignocellulosic biomass, such as thermochemical routes (gasification, pyrolysis, liquefaction) which directly process whole lignocellulose to upgradeable platforms (e.g., synthesis gas and bio-oil). The primary focus of this review is an overview of catalytic strategies to produce biofuels from aqueous solutions of carbohydrates, which are isolated through biomass pretreatment and hydrolysis. Although hydrolysis-based platforms are associated with higher upstream costs arising from pretreatment and hydrolysis, the aqueous solutions of biomass-derived compounds can be processed selectively to yield hydrocarbons with targeted molecular weights and structures. For example, sugars can be used as reforming feedstocks for the production of renewable hydrogen, or they can be dehydrated to yield furfurals or levulinic acid. For each of the platforms discussed, we have suggested relevant strategies for the formation of C–C bonds, such as aldol condensation of ketones and oligomerization of alkenes, to enable the production of gasoline, jet, and Diesel fuel range hydrocarbons. Finally, we address the importance of hydrogen in biorefining and discuss strategies for managing its consumption to ensure independence from fossil fuels.

Aldol Condensation in Water Using Polyethylene Glycol 400.

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Aldol Condensation in Water Using Polyethylene Glycol 400

Abstract Efficient and environmentally friendly synthesis of chalcones and 2,6-bis(arylmethylidene)cycloalkanones was carried out by aldol condensation of ketones with aromatic aldehydes in water in the presence of polyethylene glycol 400.

Stereocontrolled formation of spiro enones by radical cyclization of bromo acetals

Aldol condensation of ketones with 2-[[(1,1-(dimethylethyl)diphenylsilyl]oxy]propanal ( 7), dehydration, NaBH 4 reduction and treatment of the resulting alcohols with ethyl vinyl ether in the presence of NBS gives bromo acetals (e.g. 11) that undergo 5- exo-trigonal radical cyclization, affording compounds that are easily converted into spiro enones (e.g. 16). The stereochemistry at the spiro center is controlled by the stereochemistry at the hydroxyl-bearing carbon of the intermediate alcohol.

Conformational dichotomy and pyramidalized carbonyl groups in zinc aldolate chelates obtained from aldol condensations of ketones: crystallographic characterization of {[(Me3Si)2N]Zn[.mu.,.eta.2-OCR1(CH2R2)CHR2C(O)R1]}2

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTConformational dichotomy and pyramidalized carbonyl groups in zinc aldolate chelates obtained from aldol condensations of ketones: crystallographic characterization of {[(Me3Si)2N]Zn[.mu.,.eta.2-OCR1(CH2R2)CHR2C(O)R1]}2Subhash C. Goel, Michael Y. Chiang, and William E. BuhroCite this: J. Am. Chem. Soc. 1991, 113, 18, 7069–7071Publication Date (Print):August 1, 1991Publication History Published online1 May 2002Published inissue 1 August 1991https://doi.org/10.1021/ja00018a072RIGHTS & PERMISSIONSArticle Views82Altmetric-Citations11LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts