Selektiver Aufbau achtgliedriger Carbocyclen durch Ringschlussmetathese acyclischer Vorstufen

Abstract

Bei der Synthese von Cyclooctanoiden kam es in jüngster Zeit zu bemerkenswerten Fortschrittten dank der Entwicklung von hochspezifisch wirkenden Reagentien und der Entdeckung neuartiger Reaktionen. Trotzdem bleibt der direkte Aufbau achtgliedriger Carbocyclen aus acyclischen Vorstufen eine Herausforderung, da entropische und enthalpische Faktoren für die Bildung von Ringen dieser Größe nachteilig sind. Dieser Kurzaufsatz beschreibt die Anwendung der Ringschlussmetathese (RCM) als eine neue Methode zur Synthese von Cyclooctanoiden.

Chemically Controlled Conductivity: Torsion‐Angle Dependence in a Single‐Molecule Biphenyldithiol Junction

“…[23,26] Again starting from 11, a copper-mediated Grignard addition gave the diallylic biphenyl 13. Although the formation of eight-membered rings by ring-closing metathesis (RCM) was reported to be difficult, [27,28] the cyclization of 13 to give 14 proceeded smoothly, probably because the allyl chains in 13 are conformationally predisposed. Subsequent hydrogenation and reaction sequence similar to that described for 3 resulted in the replacement of the chlorines by acetylsulfanyl groups to provide the butylene-bridged BPDT derivative 4.…”

Die Totalsynthese von (−)‐Nitidasin

“…Nach stereoselektiver Addition der Lithiumspezies 4 an das Hydrindanon 5 sollte der resultierende tertiäre Alkohol 6 eine Ringschlussmetathese eingehen. [14] Die Synthese von Nitidasin sollte Abbildung 1. Aus "Hercampuri" isolierte und verwandte Sesterterpenoide.…”

Lewis Acid Catalyzed Intramolecular [4+2] and [3+2] Cross‐Cycloaddition of Alkynylcyclopropane Ketones with Carbonyl Compounds and Imines

“…

The structurally diverse and complex family of compounds that have bridged oxa/aza-[n.2.1] and oxa/aza-[n.3.1] skeletons (n = 2, 3, 4) widely occurs in nature and exhibits a broad range of biological activities (Scheme 1). [2][3][4][5] As important substructures that are prevalent in natural products, cis-2,5-disubstituted tetrahydrofuran/ pyrrolidine and cis-2,6-disubstituted tetrahydropyran/piperidine may also be obtained by CÀC bond cleavage (Scheme 2). [1] A general strategy for the construction of medium-sized carbocycles may be provided by CÀO or CÀN bond cleavage in bridged skeletons (Scheme 2).

…”

“…Additionally, such bridged skeletons can also be used as key intermediates in organic synthesis because of their inherent stereochemistry and multiple functionalizable sites. [2][3][4][5] As important substructures that are prevalent in natural products, cis-2,5-disubstituted tetrahydrofuran/ pyrrolidine and cis-2,6-disubstituted tetrahydropyran/piperidine may also be obtained by CÀC bond cleavage (Scheme 2). [2][3][4][5] As important substructures that are prevalent in natural products, cis-2,5-disubstituted tetrahydrofuran/ pyrrolidine and cis-2,6-disubstituted tetrahydropyran/piperidine may also be obtained by CÀC bond cleavage (Scheme 2).…”