Development of the Olefin Metathesis Method in Organic Synthesis
Recently, the application of olefin metathesis to small molecule synthesis has emerged as a powerful synthetic method.
metathesis method in organic synthesis
An alternative solid phase process is offered which utilizes an Ugi/ring closing metathesis reaction tandem to deliver the desired compounds in two synthetic operations.">
Given the massive number of people affected worldwide by neurodegenerative diseases and nerve injuries, it's not surprising that a number of synthetic groups have chosen to focus their research programs on neurotrophic natural products. Of course, it's probably coincidence that aside from their potential uses to society, a number of these compounds seem to also be structurally unique and strikingly intricate molecules. One such example is jiadifenolide, whose dense, caged seco-prezizaane-type structure has already seen 3 total syntheses since its isolation five years ago.
First metathesis catalyst to be widely used in organic synthesis
We have shown through selected examples that cross metathesis of an epoxide containing olefin with electron-deficient olefins constitutes a versatile entry towards trifunctional building blocks by ring-opening of the epoxide. We have shown that the tandem cross metathesis/C=C hydrogenation yielded the hydrogenated compound without altering the epoxide moiety that was further efficiently transformed into a 1,2-diol, a 1,2-alkoxy alcohol and a 1,2-amino alcohol. This strategy opens the way for numerous potential transformations involving the epoxide but also the functional group of the electron-deficient olefin. In particular, lactones should be accessible by intramolecular trans-esterification from 6, 7 and 8, as well as cyclic amines by intramolecular cyclization involving primary amine resulting from hydrogenation of the nitrile functionality in 5. All these aspects will be further developed in our group.
VI. LIST OF NAMED ORGANIC REACTIONS Bischler-Napieralski Isoquinoline Synthesis.................................................................................... ......................62
“Metathesis in Natural Product Synthesis” subtitled ..
With this protocol secured, we turned our attention to the synthesis of useful polyfunctional building blocks. Thus far, the post-transformation of the electron- deficient olefin cross metathesis partner has received attention for the synthesis of polymer precursors. For instance, we have reported the reduction of the nitrile functional group into primary amine  and the reduction of the formyl group into alcohol [–]. Herein, we focused on the post-transformation of 4 by ring-opening of the epoxide moiety. The diol 6, methoxy alcohol 7 and amino alcohol 8 were thus prepared by reacting 4 with water, sodium methoxide and aniline, respectively (). The synthesis of 6 proceeded cleanly and did not require any purification procedure (see ). Similarly, the synthesis of 7 proceeded cleanly and delivered a single regioisomer 7 in quantitative yield. Finally, the amino alcohol 8 was also obtained as a single regioisomer in 61% yield ().
Interestingly, despite the hugely varied interests and specializations of the groups involved, all five of the successful total syntheses reported to date have constructed the molecule’s prominent bicyclo[2.2.2]octane ring system using the venerable Diels–Alder reaction (often in conjunction with the similarly tried-and-true tactic of oxidative dearomatization to establish the diene). That said, the number of Diels–Alder variants employed is impressive, and you could almost imagine giving a short lecture course on the reaction using nothing but examples from synthetic studies on maoecrystal V. I’ve tried to illustrate the variety below.
of olefin metathesis as a synthetic method.
PPT - Olefin Metathesis PowerPoint Presentation - …
The invention has utility, for example, in the fields of catalysis, organic synthesis, and industrial chemistry.
Development of the Olefin Metathesis Method in Organic Synthesis
(2015)Ring-closing metathesis cascade toward a formal synthesis of taxol. PhD thesis, University of Glasgow.
Metal Carbenes in Organic Synthesis; ..
Schrock of MIT "for development of the metathesis methodin organic synthesis".
Alkene metathesis in organic synthesis - Internet Archive
The cross metathesis of 1,2-epoxy-5-hexene (1) with methyl acrylate and acrylonitrile was investigated as an entry to the synthesis of polyfunctional compounds. The resulting cross metathesis products were hydrogenated in a tandem fashion employing the residual ruthenium from the metathesis step as the hydrogenation catalyst. Interestingly, the epoxide ring remained unreactive toward this hydrogenation method. The saturated compound resulting from the cross metathesis of 1 with methyl acrylate was transformed by means of nucleophilic ring-opening of the epoxide to furnish a diol, an alkoxy alcohol and an amino alcohol in high yields.
Alkene metathesis in organic synthesis Item Preview
In this article we present our results aimed at extending the scope of sequential transformations including cross metathesis to the synthesis of trifunctional compounds. Several examples involving the cross metathesis of a commercially available epoxide-containing olefin with methyl acrylate and acrylonitrile and their subsequent transformations leading to multifunctional building blocks are reported.
Organic SCENE Keywords: synthesis, cross metathesis…
An alternative solid phase process is offered which utilizes an Ugi/ring closing metathesis reaction tandem to deliver the desired compounds in two synthetic operations.
Described are methods of making organic compounds by metathesis ..
Thisarticle tells the story of how olefin metathesis became a truly usefulsynthetic transformation and a triumph for mechanistic chemistry, andillustrates the importance of fundamental research.
Methods of making organic compounds by metathesis and ..
AB - Olefin metathesis is established as a remarkably valuable synthetic tool in current organic chemistry. We report here total synthesis of natural products using sequential olefin metathesis reactions. The one - pot ring - opening/cross/ring - closing metathesis (ROM/CM/RCM) reaction has been developed, allowing for the concise construction of the oxygen - bridged 1,3 - cycloocta-diene framework from an oxanorbornene derivative and 1,3-butadiene. The ROM/CM/RCM product was converted into (+)-mycoepoxydiene, (-)-1893A, and (+)-1893B. Furthermore, the ring - opening/ring - closing metathesis (ROM/RCM) of cyclobutenecarboxylate derivatives has been developed as a novel method for access to γ- butenolides. The enantioselective total synthesis of (+)-clavilactone A and (-)-clavilactone B was achieved by the use of this reaction (ROM/RCM).
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