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Enol Acetates (enol + acetate)

Distribution by Scientific Domains

Chemistry	100%

Distribution within Chemistry

General & Introductory Chemistry	66%
Organic Chemistry	33%

Selected Abstracts

Computational Investigation of 1,3-H and 1,5-H Shifts in Isomerization of Enol Acetate of 2-Aceto-1,3-cyclohexanedione

CHINESE JOURNAL OF CHEMISTRY, Issue 6 2009
Yanhua WANG
Abstract The mechanism of the isomerization of the enol acetate of 2-aceto-1,3-cyclohexanedione has been discussed in detail. The possible 1,3-H and 1,5-H shifts in isomerization were investigated systematically. It seems that this mechanism includes two successive 1,5-sigmatropic shifts, i.e. 1,5-acetyl and 1,5-H shifts. Density functional theory calculations have been performed to evaluate the reasonability of the proposed mechanisms. The effect of the solvent upon the rate-determining steps has been also considered. In addition, the relative stabilities of the reactant, the product as well as the intermediates in the proposed mechanism have been examined and discussed. [source]

,-Alkylation of Carbonyl Compounds by Direct Addition of Alcohols to Enol Acetates,

ANGEWANDTE CHEMIE, Issue 48 2009
Yoshihiro Nishimoto Dr.
A praktische ,-Alkylierung von Ketonen und Aldehyden gelingt mit der Titelreaktion. Die moderate Lewis-Acidität von InI3, GaBr3 und FeBr3 ist ein Schlüsselfaktor des Katalysezyklus, und eine Vielzahl unterschiedlicher Alkohole und Enolacetate wurde erfolgreich eingesetzt. [source]

ChemInform Abstract: Desymmetrization of 4,4-Disubstituted Cyclohexanones by Enzyme-Catalyzed Resolution of Their Enol Acetates.

CHEMINFORM, Issue 10 2001
Graham Allan
Abstract ChemInform 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. [source]

Platinum- and Gold-Catalyzed Rearrangement Reactions of Propargyl Acetates: Total Syntheses of (,)-,-Cubebene, (,)-Cubebol, Sesquicarene and Related Terpenes

CHEMISTRY - A EUROPEAN JOURNAL, Issue 11 2006
Alois Fürstner Prof.
Abstract Propargyl acetates, in the presence of catalytic amounts of late transition-metal salts such as PtCl2 or AuCl3, represent synthetic equivalents of ,-diazoketones. This notion is corroborated by a concise approach to various sesquiterpene natural products starting from readily available substrates. Specifically, (+)-carvomenthone (17) is converted into propargyl acetate (S)- 26 by a sequence involving Stille cross-coupling of its kinetic enol triflate 18, regioselective hydroboration/oxidation of the resulting 1,3-diene 19, and addition of an alkynyl cerium reagent to aldehyde 21 thus obtained. Since the latter step was found to be unselective, the configuration of the reacting propargyl acetate was unambiguously set by oxidation followed by diastereoselective transfer hydrogenation by using Noyori's catalyst 25. Compound (S)- 26, on treatment with PtCl2 in toluene, converted exclusively to the tricyclic enol acetate 27, which was saponified to give norcubebone 11 in excellent overall yield. The conversion of this compound into the sesquiterpene alcohol (,)-cubebol (6) was best achieved with MeCeCl2 as the nucleophile, whereas the formation of the parent hydrocarbon (,)-,-cubebene (4) was effected in excellent yield by recourse to iron-catalyzed cross coupling methodology developed in this laboratory. Since norketone 11 has previously been transformed into (,)-,-cubebene (5) as well as (,)-4-epicubebol 8, our approach constitutes formal total syntheses of these additional natural products as well. Along similar lines, the readily available propargyl acetates 1, 33 and 47 were shown to give access to 2-carene 44, sesquicarene 39, and episesquicarene 51 in excellent overall yields. In this series, however, the cycloisomerization reaction was best achieved with catalytic amounts of AuCl3 in 1,2-dichloroethane as the solvent. In addition to these preparative results, our data provide some insight into the mechanism of these remarkable skeletal rearrangement reactions. Transformations of this type are likely triggered by initial coordination of the alkyne unit of the substrate to the carbophilic transition-metal cation. Formal attack of the alkene moiety onto the resulting ,-complex engenders the formation of an electrophilic cyclopropyl carbene species which subsequently reacts with the adjacent acetate unit to give the final product. The alternative phasing of events, implying initial attack of the acetate (rather than the alkene moiety) onto the metal,alkyne complex, is inconsistent with the stereochemical data obtained during this total synthesis campaign. [source]

Computational Investigation of 1,3-H and 1,5-H Shifts in Isomerization of Enol Acetate of 2-Aceto-1,3-cyclohexanedione

DiPAMP's Big Brother "i- Pr-SMS-Phos" Exhibits Exceptional Features Enhancing Rhodium(I)-Catalyzed Hydrogenation of Olefins

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 17 2009
Michel Stephan
Abstract Switching Knowles DiPAMP's {DiPAMP=1,2-bis[(o -anisyl)(phenyl)phosphino]- ethane} MeO groups with i- PrO ones led to the i- Pr-SMS-Phos {i- Pr-SMS-Phos=1,2-bis[(o -isoprop- oxyphenyl)(phenyl)phosphino]ethane} ligand which displayed a boosted catalyst activity coupled with an enhanced enantioselectivity in the rhodium(I)-catalyzed hydrogenation of a wide-range of representative olefinic substrates (dehydro-,-amido acids, itaconates, acrylates, enamides, enol acetates, ,,,-diarylethylenes, etc). The rhodium(I)-(i- Pr-SMS-Phos) catalytic profile was investigated revealing its structural attributes and robustness, and in contrast to the usual trend, 31P,NMR analysis revealed that its methyl (Z)-,-acetamidocinnamate (MAC) adduct consisted of a reversed diastereomeric ratio of 1.4:1 in favour of the most reactive diastereomer. [source]