Acid-promoted Reaction Research Articles

Diastereoselective ring-opening aldol-type reaction of 2,2-dialkoxycyclopropanecarboxylic esters with carbonyl compounds. 1. Synthesis of cis 3,4-substituted .gamma.-lactones

The Lewis acid-promoted reactions of 2,2-dialkoxycyclopropanecarboxylic esters 4a-c with aldehydes and unsymmetrical ketones to give γ-lactones were investigated. TiBr 4 is an excellent catalyst and gives cis 3,4-substituted γ-lactones in good yields with high diastereoselectivity. SnBr 4 promotes the reaction of 4a-c with aldehydes with high cis-selectivity, but does not promote the reaction of 4a with unsymmetrical ketones. ZrCl 4 is moderately trans-selective in the reaction of 4a with unsymmetrical ketones. Cis γ-lactones can be converted into their trans-isomers by treatment with NaOEt in EtOH

Lewis Acid-Promoted Reaction of β,β-Difluorinated N,O-Acetal with Silylated Nucleophiles

Abstract Lewis acid-promoted reaction of ethyl 3-ethoxy-2,2-difluoro-3-(dimethylamino)propionate (1) with some silylated nucleophiles afforded β,β-difluoroamines in good yields. The formation of iminium ion intermediate from 1 and BF3·OEt2 was confirmed by 19F and 13C NMR spectroscopy.

Biomimetic synthesis of theonellin isocyanide

A marine sesquiterpene of the theonellin class has been synthesized for the first time. Direct amination of the theonelline carbon framework 2 in a biometric fashion, a crucial step, was achieved by employing a triflic acid-promoted Ritter-type reaction at low temperature (–78 °C ).

Unsual ε/γ-regiospecificity of (E/Z)-pentadienyltin in the Lewis acid-promoted reaction with an aldehyde

In the Lewis acid-promoted reaction between pentadienyltin (PDT) and an aldehyde, (E)-and (Z)-PDTs exhibit opposite regioreactivities: (E)-PDT reacts at the terminal Iµ-position and (Z)-PDT at the internal γ-position.

ChemInform Abstract: Acid‐Promoted Reaction of Cyclic Allylic Diols with Carbonyl Compounds. Stereoselective Ring‐Enlarging Tetrahydrofuran Annulations.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 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.

Cyclisation chemistry of some functionalised allylsilanes

Two allylic silanes bearing additional functionality in the form of either a bromide or a phenylsulphonyl group were synthesised and condensed with a variety of electrophilic partners. Subsequent cyclisation of some of the products was then possible by utilising the acid-promoted reactions of the allylsilane grouping, to give one spiropentannulated product ( 8) and two medium ring ether sulphones ( 12) and ( 13).

Acid-promoted reaction of cyclic allylic diols with carbonyl compounds. Stereoselective ring-enlarging tetrahydrofuran annulations

A wide variety of cis-fused hexahydrocyclopenta [b] furan-4-ones (3, n=0), hexahydro-4(2H)-benzofuranones (3, n=1), and octahydrocyclohepta [b] furan-4-ones (3, n=2) can be prepared with high levels of stereocontrol by the title reaction. The scope and limitations of this powerful new method for assembling polycyclic ethers are explored in detail. Conformational analysis of potential oxabicyclo [4.4.0] decanyl, oxabicyclo [4.3.0] nonanyl, and oxabicyclo [4.2.0] octanyl cation intermediates allows the stereochemical outcome of the title reaction to be predicted

Kurzmitteilung / Short Communication. Acid‐Catalyzed and Lewis Acid‐Promoted Synthesis of 6‐Hydroxybicyclo[4.3.0]nonan‐3‐ones

3a‐Hydroxy‐6‐hydrindanones of type 10 and 11 can be obtained by acid‐catalyzed or Lewis acid‐promoted cyclization reactions of ene‐ketals of type 6 and 7. The compounds described are interesting building blocks for biologically active heart glycosides.

Synthesis of Unsymmetrically Substituted Benzils via the Friedel-Crafts Reaction of Arenes with .ALPHA.-Chloro-.ALPHA.-(methylthio) acetophenones.

Lewis acid-promoted reactions of arenes with α-chloro-α-(methylthio)acetophenones 6-8 gave the Friedal-Crafts reaction products 9, which were then treated with 3 molar eq of cupric chloride in aqueous acetone to afford the unsymmetrically substituted benzils 10.

Thermal and Lewis acid-promoted novel asymmetric hetero Diels–Alder reactions of a 1-thiabuta-1,3-diene system (thiochalcones) with (–)-dimenthyl fumarate

Thermal and Lewis acid-promoted reactions of thiochalcones with (–)-dimenthyl fumarate gave two 3,4-cis-cycloadducts, 4 and 5, in good yields with 100%endo-diastereoselectivity and with a high level of diastereofacial selectivity. The major product 4 could be obtained stereochemically pure by recrystallization and this, when reduced with LiAlH4, gave the optically active diol 6. The latter was converted into the acyclic diol 8 by Raney-Ni desulphurization.

Kinetics of Acid-Hydrolysis of Nickel(II) and Copper(II) Compounds With the Cyclic Diamines 1,5-Diazocane and 4,4-Dimethyl-7-(5,5,7-trimethyl-1,4-diazepan-1-Yl)-5-azaheptan-2-ol

The kinetics of acid-promoted hydrolysis reactions of nickel(II) and copper(ll) complexes of the cyclic diamines 1,5-diazocane ( daco ) and 4,4-dimethyl-7-(5,5,7-trimethyl-1,4-diazepan-1-yl)-5-azaheptan-2-ol (pyaz) in NaCl/HCl media ([Cl-] = 2 mol dm-3) are reported. For [Ni( daco )2]2+, beyond small [H+], an acid-limited rate constant of 2.0×10-5 S-l, involving dissociation of the first daco ligand, and for [Cu( daco )2]2+ a similarly acid-limited rate constant of 1.5×10-2 s-l, involving dissociation of the second daco ligand, were measured at 50°C. For [Ni( pyaz )]2+ and [Cu ( pyaz )2+ the rates of the hydrolysis reactions are again acid-limited, effectively independent of acid with rate constant of 1.0×10-2 s-1 for [Ni( pyaz )]2+ while for [Cu( pyaz )]2+ the rate follows the expression kobs , = 6.0×10-2[H+]/(l+4.6[H+]) S-l, both measured at 25°C.

Lewis acid-promoted reactions of substituted pentacyclo[5.4.0.02,6.03,1005,9]undecane-8,11-diones with ethyl diazoacetate

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLewis acid-promoted reactions of substituted pentacyclo[5.4.0.02,6.03,1005,9]undecane-8,11-diones with ethyl diazoacetateAlan P. Marchand, Pendri Annapurna, S. Pulla Reddy, William H. Watson, and Ante NaglCite this: J. Org. Chem. 1989, 54, 1, 187–193Publication Date (Print):January 1, 1989Publication History Published online1 May 2002Published inissue 1 January 1989https://doi.org/10.1021/jo00262a041RIGHTS & PERMISSIONSArticle Views266Altmetric-Citations18LEARN 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 (981 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Stepwise intramolecular cycloaddition of nitrile oxide equivalents derived from the Lewis acid-promoted reaction of 1-nitroalkadienes and allylic stannanes

The Lewis acid-promoted reaction of 1-nitroalka-1,5-(or 1,6-)dienes with allylic stannanes has been studied. In the presence of TiCl4, 1-nitrohexa-1,5-diene reacted smoothly with allyltrimethylstannane to give a diastereoisomeric mixture of 6-allyl-3a,4,5,6-tetrahydro-3H-cyclopent[c] isoxazoles, while the reaction using AlCl3 as catalyst led to an allylated cyclohexanone oxime derivative in good yield. The similar reaction of 1-nitrohepta-1,6-diene, however, gave a bicyclic dihydroisoxazole irrespective of the Lewis acids employed. In the latter case, nitrite oxide equivalents derived from 1-nitroalka-1,6-dienes underwent a stepwise cycloaddition as shown by the lack of stereospecificity in the reactions of (1E,6Z)-1-nitro-7-phenylhepta-1,6-diene and (1E,6Z)-1-nitro-octa-1,6-diene.

ChemInform Abstract: Trifluoromethanesulfonic Acid‐Promoted Reaction of Hexahydro‐1,3,5‐triazines.

AbstractDie Hexahydrotriazine (I) setzen sich mit den Ketensilylacetalen (II) in Gegenwart katalytischer Mengen Trifluormethansulfonsäure zu den sekundären β‐Aminosäureestern (III) um.

Trifluoromethanesulfonic acid-promoted reaction of hexahydro-1,3,5-triazines. Introduction of a secondary aminomethyl grouping into carboxylates at the .ALPHA.-position through ketene silyl acetals.

Synthese de β-alkylaminocarboxylates d'alkyle par reaction de (perhydro trialkyl-1,3,5) triazines-1,3,5 avec des [methyl trimethylsilyl] acetals de cetenes en presence d'acide trifluoro methanesulfonique

A photochemical route to the protoberberine skeleton

Irradiation of Mannich bases obtained from phthalimides, formaldehyde, and 1,2,3,4-tetrahydroiso-quinolines and carrying methoxy or methylenedioxy substituents gave, in moderate yield, pentacyclic photoproducts. These underwent acid-promoted reaction leading to 13-hydroxydibenzo-[a,g]quinolizin-8-ones, one of which was 13-hydroxy-8-oxoxylopinine. Reduction to remove the 8,13 oxygenated functions was not achieved. Unsymmetrical substrates derived from 3,4-dimethoxyph-thalimide gave a mixture of regio- and stereo-isomers in the photocyclisation, with no strong preference for one orientation of reaction.

Trifluoromethanesulfonic acid-promoted reaction of hexahydro-1,3,5-triazines with ketene silyl acetals. convenient synthesis of alkyl β-aminocarboxylates

A new, convenient synthesis of alkyl β-aminocarboxylates has been achieved by a reaction of hexahydro-1,3,5-triazines with ketene silyl acetals in the presence of catalytic amount of trifluoromethanesulfonic acid.

ChemInform Abstract: TOTAL SYNTHESIS OF CURZERENONE AND EPICURZERENONE

AbstractDer aus dem Ketenacetal (I) mit dem Nitropropen (II) leicht zugängliche Ketoester (III) wird nach Homologisierung mit Diazomethan (IV) zum Ketoester (V) zum Cyclohexandion (VI) cyclisiert.

TOTAL SYNTHESIS OF CURZERENONE AND EPICURZERENONE

Abstract Curzerenone and epicurzerenone were synthesized by means of a combination of γ-ketoester synthesis and 3-methylfuran annulation both of which utilize nitroolefins as synthons. Starting material, methyl 2-methyl-4-oxo-2-vinylpentanoate, was prepared by the Lewis acid-promoted reaction of l-methoxy-2-methyl-l-[(trimethylsily)oxy]-1,3-butadiene and 2-nitropropene, while key intermediate 3,6-dimethyl-6-vinyl-6,7-dihydrobenzofuran-4(5H)-one was assembled by the KF-catalyzed reaction of 5-methyl-5-vinylcyclohexane-l,3-dione and 1-nitro-1-phenylthiopropene.

ChemInform Abstract: THE AMINATION AND DIMERIZATION OF NORBORNADIENE WITH NICKEL, PALLADIUM, AND RHODIUM COMPLEXES

AbstractWährend Norbornadien (III) mit dem System Bis phin (Ni(COD)2 Bu3P) z.B. in Morpholin (II) bei 90°C nur zum Dimeren (I) reagiert, entstehen unter analogen Bedingungen in Gegenwart von Trifluoressigsäure (TFE) das Dimere (IV) und das Norbornen (V).