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Synthetic Equivalents (synthetic + equivalent)

Distribution by Scientific Domains

Chemistry	91%

Distribution within Chemistry

Organic Chemistry	72%
General & Introductory Chemistry	17%

Selected Abstracts

Divinyl Sulfide as Synthetic Equivalent of Ethenethiolate and 3-Butenethiolate Anions in Nucleophilic Substitution in Halopyridines and Haloalkanes.

CHEMINFORM, Issue 26 2004
S. V. Amosova
No abstract is available for this article. [source]

ChemInform Abstract: 7,7-Dimethyl-6,8-dioxabicyclo[3.3.0]oct-3-en-2-one as a Synthetic Equivalent of Ketodicyclopentadiene: A New Route to (-)-Physostigmine, (-)-Physovenine, and (-)-Aphanorphine.

CHEMINFORM, Issue 22 2001
Keigo Tanaka
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]

Synthesis of Polyfluorinated Nitrogen-Containing Heterocycles from Hemifluorinated Enones or Organofluorosilicon Building Blocks as Synthetic Equivalents

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 7 2004
Frédéric Chanteau
Abstract A series of polyfluorinated heterocycles has been prepared by heterocyclisation of hemifluorinated enones or organofluorosilicon synthetic equivalents with different bis(nucleophiles). These polyfluorinated building blocks were obtained by treatment of acylsilanes with perfluoro organometallic reagents. The method is general and has been applied to aliphatic, aromatic and carbohydrate derivatives, to give oxazolidines, imidazolidines, benzodia- and -thiazepines, quinolines and pyrimidines bearing both a fluorine atom and a perfluoroalkyl group in vicinal positions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

ChemInform Abstract: Phosphole-N-phenylmaleimide [4 + 2] Cycloadducts as Synthetic Equivalents of Nucleophilic Phosphinidenes.

CHEMINFORM, Issue 37 2009
Rongqiang Tian
Abstract ChemInform 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. [source]

ChemInform Abstract: Amphoteric Character of 2-Vinyloxiranes: Synthetic Equivalents of ,,,-Unsaturated Aldehydes and a Vinylogous Enolate.

CHEMINFORM, Issue 13 2001
Mark Lautens
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]

Synthesis of Substituted 1,3-Diene Synthetic Equivalents by a Ru-Catalyzed Diyne Hydrative Cyclization

CHEMISTRY - AN ASIAN JOURNAL, Issue 3 2006
Barry
Abstract Catalyzed by [CpRu(CH3CN)3]PF6, the hydrative cyclization of dipropargylic sulfone substrates provides an effective way to synthesize highly functionalized substituted 3-sulfolenes. The amount of water is crucial for the reactivity of this cycloisomerization reaction. The scope and limitations of the Ru-catalyzed cycloisomerization are discussed. A marked ketone-directing effect was observed for the first time in ruthenium-catalyzed cyclizations. A plausible mechanism for the ketone-directed cycloisomerization is also rationalized. The utility of this method was demonstrated by both sulfur dioxide extrusion of the 3-sulfolenes to afford 1,3-dienes and subsequent inter- or intramolecular Diels,Alder reactions. [source]

Comparison of genuine (1851,1852 AD) and forged or reproduction Hawaiian Missionary stamps using Raman microscopy

JOURNAL OF RAMAN SPECTROSCOPY, Issue 6 2002
Tracey D. Chaplin
The rare and valuable Hawaiian Missionary stamps from the Tapling Collection held at the British Library were analysed using Raman microscopy and shown to be printed with an ink composed of Prussian blue. Blue particles dispersed between the paper fibres of the stamps and present as optical brighteners were identified to be lazurite or the synthetic equivalent, ultramarine blue. Each cancellation or postmark, where present, is composed of carbon, vermilion, iron(III) oxide or a madder-like organic pigment. The Raman analysis also showed that microscopic repair work on stamps can be identified. The genuine stamps were compared with 13 forged Hawaiian Missionary stamps, printed in the early 20th century, and with a set of eight reproduction items printed in 1985, from the Royal Philatelic Society London. Raman analysis of the forged stamps showed that the ink used is different from that of the genuine stamps, being a mixture of Prussian blue and ultramarine blue, or an organic blue pigment. Analysis of the 1985 reproduction stamps showed that they were printed with modern phthalocyanine blue ink, on paper coated with a yellow organic pigment to simulate aged paper. This analysis provides an invaluable and non-destructive method for assisting in drawing a distinction between fraudulent or reproduction material and the genuine article. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Syntheses of O6 -Alkyl- and Arylguanine Derivatives: Nucleobase Adducts Derived from Styrene 7,8- and 3,4-Oxides

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 2 2006
Jan Novák
Abstract A series of O6 -alkyl and -arylguanine derivatives that may be formed in vivo after exposure to styrene has been prepared by reaction of 6-(4-aza-1-azoniabicyclo[2.2.2]octyl)-purine with alkoxides and aryloxides, respectively. Themonoprotected diols 2-allyloxy- or 2-benzyloxy-1-phenylethanol and 2-allyloxy- or 2-benzyloxy-2-phenylethanol were used as synthetic equivalents of styrene 7,8-oxide. 4-Vinylphenol, 2-(4-hydroxyphenyl)ethanol and 4-hydroxyphenylacetic acid were used as synthetic equivalents of arene oxide metabolites of styrene, i.,e., styrene 3,4-oxide, 4-(2-hydroxyethyl)benzene 1,2-oxide and 4-carboxymethylbenzene 1,2-oxide, respectively. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

Synthesis of Polyfluorinated Nitrogen-Containing Heterocycles from Hemifluorinated Enones or Organofluorosilicon Building Blocks as Synthetic Equivalents

Zinc-Salen-Catalyzed Asymmetric Alkynylation of Alkyl Acylsilanes

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2009
Feng-Quan Li
Abstract Optically active tertiary propargylic alcohols are useful and versatile building blocks in organic synthesis, and their direct access by enantioselective addition of alkyne nucleophiles to ketones has achieved significant progress over the last ten years. In view of the potential applications of acylsilanes as useful synthetic equivalents of aldehydes, we described a general catalytic enantioselective addition of terminal alkynes to alkyl acylsilanes. After reaction optimization involving variation of solvent, temperature, catalyst ratio and various catalysts screen, the in situ generated Zn-salen complex was chosen as catalyst. With hexane as solvent, the silylated tertiary propargylic alcohols were obtained in satisfactory yields and ees for both aliphatic and aromatic alkynes. [source]

Development of a synthetic plant volatile-based attracticide for female noctuid moths.

AUSTRALIAN JOURNAL OF ENTOMOLOGY, Issue 1 2010

Abstract This paper reports olfactometer studies to determine the attractiveness of synthetic equivalents of plant volatiles to Helicoverpa armigera (Hübner) moths. Synthetic volatiles identified from host plants and other volatiles reported in literature as attractants to various noctuid species were tested in a two-choice olfactometer. Of 34 single chemicals tested, only seven were significantly attractive, and six were significantly repellent. However, when presented as blends of two or more volatiles, 21 of 31 blends tested were significantly attractive, and only one was significantly repellent. The most attractive blends were those containing four to six components, including aromatic volatiles primarily found in flowers, especially 2-phenylethanol and phenylacetaldehyde and volatiles found primarily in leaves, including green leaf volatiles and terpenoids. Some general principles in blending volatiles for developing attracticides for H. armigera are presented, including the need for blend complexity, the combination of volatiles from leaves and flowers, and early consideration of pragmatic factors such as price and toxicological profile. [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]