Olefin Methathesis Research Articles

Pharmaceutical Green Chemistry Applied to the Chemical Synthesis of Steroid Compounds

Steroid compounds are widely distributed in nature and are challenging substrates for the synthesis of a wide variety of important biologically active molecules. These include the sex hormones, corticosteroids and mineralocorticoids hormones, bile acids, vitamin D derivatives, cardiotonic steroids, among others, that have shown great therapeutic value for a broad array of medical conditions. Due to their biological and synthetic relevance, several chemical processes for the preparation and/or functionalization of the steroid nucleus have been developed. In some of those processes, green chemistry principles have been incorporated, allowing significant advances in synthetic chemistry applied to steroid compounds. In this review, a selection of the most relevant applications of pharmaceutical green chemistry in steroid synthesis, using chemical methods will be presented. Special emphasis will be given to catalytic processes, specially involving the use of heterogeneous catalysts, microwave technologies and ionic liquids as solvents. This review is organized according to the reaction type that include oxidation and reduction reactions, protection/deprotection transformations, glycosylations, rearrangements, olefin methathesis, preparations of heterocycles using different strategies and miscellaneous reactions. Biocatalytic methods applied to steroid synthesis are out of the scope of this review. Keywords: Alternative solvents, catalysis, green technologies, pharmaceutical green chemistry, steroids.

ChemInform Abstract: A Synergistic Approach to Polycyclics via a Strategic Utilization of Claisen Rearrangement and Olefin Methathesis

AbstractReview: 123 refs.

ChemInform Abstract: Hoveyda—Grubbs′ Catalyst Confined in the Nanocages of SBA‐1: Enhanced Recyclability for Olefin Metathesis.

AbstractImmobilization of the second generation Hoveyda—Grubbs′ catalyst on mesoporous silica SBA‐1 via a simple adsorption gives a highly recyclable solid catalyst for olefin methathesis reactions.

ChemInform Abstract: Efficient Synthesis Routes to Aromatic Compounds Using Ring‐Closing Olefin Methathesis Followed by Dehydration, Oxidation, and Tautomerization.

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.

Syntheses of (−)-(7 S)- and (+)-(7 R)-K252a dimers

This letter describes syntheses of (−)-(7 S)-and (+)-(7 R)-K252a dimers wherein a convergent bis-indole- N-glycosidic coupling step was used for the resolution of the C(7) substituted (±)-aglycon. Dimerization of the derived monomers was achieved via olefin methathesis.

Olefin metathesis–recent applications in synthesis

Olefin methathesis allows for the catalytic cleavage and formation of C,C multiple bonds under mild conditions in the presence of various functional groups. Whereas ring closing metathesis has been widely used in the synthesis of cyclic olefins, less applications have been described for other metathesis types, namely cross and ring opening metathesis. The combination of these two reactions in domino processes and their application to the synthesis of complex natural products is described.

ChemInform Abstract: Hydroxylated α‐Vinylpyrrolidines from Sugar‐Derived 2,5‐Dihydrofurans. Synthesis of (1S,2S,8aR)‐1,2‐Dihydroxyindolizidine by Ring Closing Olefin Methathesis.

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.

Olefin metathesis offers 'perfect' polyethylene

Using olefin metathesis, chemists at the University of Florida, Gainesville, have produced polyethylene resins that have strictly ordered branches or end groups. Their work may furnish perfect forms of polyethylene that could contribute to understanding real-world resins made by commercial polymerization. Several companies produce linear low-density polyethylene resins that owe their desirable processing and physical properties to some control of branching by use of various α-olefins as comonomers. For example, 1-hexene as comonomer contributes n -butyl groups spaced approximately according to the concentration of 1-hexene. Using olefin methathesis, however, the Florida researchers can do even better, polymer chemistry professor Kenneth B. Wagener told the Division of Polymer Chemistry: They make a resin that has a methyl group precisely every ninth carbon atom. Although olefin metathesis is a chain reaction, it may be pictured as a process in which two olefins combine to form a cyclobutane ring, then b...

Kinetics and mechanism of the reaction of photogenerated (η1-(tetrachloromethane) pentacarbonylmetal(O) complexes, (η1-(CCl4)M(CO)5; M = Mo, W) with 1-hexene: The initial steps in the creation of olefin methathesis catalysts

The initial steps in the formation of the heterogeneous olefin methathesis catalysts produced by photolysis of M(CO)6/CCl4 solutions (M = Mo, W) have been studied by pulsed laser flash photolysis with infrared and visible detection. In both systems, (Cl3CCl)M(CO)5 (datively bonded to M through a single Cl) is produced immediately after the flash. In the presence of the trapping nucleophile, 1-hexene (hex), this species affords (η2-hex)M(CO)5. For M = W, there is also a competitive unimolecular decay pathway which affords the solid catalyst. Infrared and rate data for (Cl3CCl)W(CO)5 and related complexes suggest that CCl4 bonds weakly to W and is a poor net donor of charge to the metal atom, which could promote fast oxidative addition of CCl4 to [M(CO)5]. The rate-determining step for the unimolecular pathway is envisioned to involve slow decomposition via CO loss of the possible oxidative addition product to afford the heterogeneous catalyst.

10th International symposium on olefin methathesis and polymerization (ISOM 10)

10th International symposium on olefin methathesis and polymerization (ISOM 10)

ChemInform Abstract: HALO‐NITROSYL‐CARBONYL‐TUNGSTEN COMPLEXES AND THEIR TRIPHENYLPHOSPHINE DERIVATIVES AS OLEFIN METHATHESIS CATALYSTS

Chemischer InformationsdienstVolume 14, Issue 9 Preparative Organic Chemistry ChemInform Abstract: HALO-NITROSYL-CARBONYL-TUNGSTEN COMPLEXES AND THEIR TRIPHENYLPHOSPHINE DERIVATIVES AS OLEFIN METHATHESIS CATALYSTS A. E. CREASE, A. E. CREASESearch for more papers by this authorH. EGGLESTONE, H. EGGLESTONESearch for more papers by this authorN. TAYLOR, N. TAYLORSearch for more papers by this author A. E. CREASE, A. E. CREASESearch for more papers by this authorH. EGGLESTONE, H. EGGLESTONESearch for more papers by this authorN. TAYLOR, N. TAYLORSearch for more papers by this author First published: March 1, 1983 https://doi.org/10.1002/chin.198309158Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume14, Issue9March 1, 1983 RelatedInformation

Halo-nitrosyl-carbonyl-tungsten complexes and their triphenylphosphine derivatives as olefin methathesis catalysts

The tungsten complexes W(CO) 4(NO)X, W(CO) 3(NO)(PPh 3)X and W(CO) 2(NO)(PPh 3) 2X (X = Cl, Br and I) have been shown to be effective catalysts for the metathesis of 1,7-octadiene.

Specialty chemicals via olefin metathesis

A wide variety of specialty chemicals are now available from technology based on the olefin metathesis reaction. This versatile reaction allows the conversion of simple, relatively inexpensive olefins into specialty, high-purity olefins which are useful intermediates in the fragrance, agricultural, and many other specialty chemical industries. In addition to originating the technology for the first commercial application of olefin methathesis (the Triolefin Process for converting propylene into high-purity ethylene and butenes), Phillips Petroleum Company R & D has been active in developing the technology for the preparation of many specialty olefins. Neohexene, an intermediate in the synthesis of musk perfume, is produced commercially in a plant completed in 1980; the reaction involves cometathesis of diisobutylene with ethylene. Developmental quantities of α,- ω-diolefins, intermediates in the preparation of agricultural chemicals, are synthesized by the reaction of ethylene with selected cyclic olefins. Alpha olefins and isomerically pure internal olefins are readily produced via olefin metathesis chemistry. The development of a new class of catalysts allows the methathesis of certain functional olefins. Olefin metathesis is being established as a valuable synthetic tool which is providing increasing access to numerous specialty chemical markets.

Synthese de macrolides par methathese.

Two syntheses of macrolides via olefin methathesis are presented. The first (A) involves preparation of ω-hydroxyacid 6 or 9 by metathesis followed by cyclisation, while the second (B) involves macrocyclic ring closure by metathesis of a ω,ω′diunsaturated ester 12 .