A Catalytic Homo-Nazarov Cyclization Protocol for the Synthesis of Heteroaromatic Ring-Fused Cyclohexanones

Phun, Lien H.; Patil, Dadasaheb V.; Cavitt, Marchello A.

doi:10.1021/ol200305n

Cited by 53 publications

(16 citation statements)

References 31 publications

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“…Dabei wurde das Cyclopropylketon 112 mit katalytischen Mengen p-Toluolsulfonsäure umgesetzt, woraufhin eine Ringerweiterung zum Sechsring 113 erfolgte (Schema 23). [105] Waser und Mitarbeiter entwickelten eine formale Totalsynthese des Alkaloids Aspidospermidin.…”

Section: Umlagerungen Zweier Cyclopropaneunclassified

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Ein neues goldenes Zeitalter in der Chemie Donor‐Akzeptor‐substituierter Cyclopropane

2014

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95 %, -, 90 % ee [b] [a] Aryl = H/Cl/Br/OMe/NO 2 -Ph, 1-Naphthyl, Styryl; R = o/p-OMe, m-NHBoc, m-Cl, o-Br, p-CF 3 ; R' = H, Alk, H; R'' = Me, Ph, Bn, Allyl; Bn = Benzyl, Boc = tert-Butoxycarbonyl, Nu = Nukleophil, LA = Lewis-Säure. [b] Einsatz enantiomerenreiner Dreiringverbindungen. [c] In situ durch NaN 3 und NH 4 Cl. Donor-Akzeptor-substituierte Cyclopropane Angewandte Chemie 5611 Schema 11. a) Aufbau von Bicyclen des Typs 45; b) intramolekulare Ringerweiterung von gem-Carbonyl-Alkinyl-Cyclopropanen 44 c. Schema 12. Formale [8+3]-Cycloaddition von D-A-Cyclopropanen mit Tropon-Derivaten 48.

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Section: Umlagerungen Zweier Cyclopropaneunclassified

“…[104] Konzeptionell ähnliche Reaktionen wurden von France et al zur Herstellung von Pyridoindolen und verwandten Verbindungen herangezogen. [105]…”

Section: Umlagerungenunclassified

Ein neues goldenes Zeitalter in der Chemie Donor‐Akzeptor‐substituierter Cyclopropane

2014

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“…With the scope of the transformation established, we envisioned the development of a one‐pot, tandem cyclopropanation/formal homo‐Nazarov cyclization sequence. This would take advantage of tandem catalysis, in which both the cyclopropanation catalyst (Rh 2 esp 2 ) and the cyclization catalyst (In(OTf) 3 ) are both present at the outset (Scheme ) . The protocol using 3‐furyl α‐diazo‐β‐ketoester 41 and 4‐methoxystyrene with Rh 2 esp 2 (1 mol %) and 0.2 mol % (In(OTf) 3 ) afforded the desired cyclohexanone 39b in 56 % yield, which is slightly higher yielding than the linear two‐step sequence (53 % over 2 steps).…”

Section: Appendage Manipulation‐based Dos Approachesmentioning

confidence: 99%

The Catalytic, Formal Homo‐Nazarov Cyclization as a Template for Diversity‐Oriented Synthesis

Martín

Shenje

2016

Israel Journal of Chemistry

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Since the formal characterization of diversity‐oriented synthesis (DOS), identification of effective examples of DOS remains an important endeavor for synthetic and pharmaceutical chemists requiring new strategies to generate broader skeletal diversity. Over the last decade, the formal homo‐Nazarov cyclization has been an increasingly popular strategy for the concise assembly of functionalized six‐membered rings due to the advent of catalytic methods to promote the transformation under milder reaction conditions. Moreover, using the formal homo‐Nazarov cyclization as a mechanistic template, reactions can be strategically devised as an effort towards diversity‐oriented synthesis. The resulting “homo‐Nazarov‐inspired” reactions are then demonstrated as a means to access broad structural diversity. This review discusses the development of these catalytic approaches and the successful implementation of the formal homo‐Nazarov reaction as a viable template for diversity‐oriented synthesis.

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“…We examined this approach for the first time in 2009 11. In 2010, France and co‐workers reported the use of the same class of substrates using indium catalysts, which allowed them to extend significantly the scope of the reaction 7h–i. Apart for enhancing the reactivity, we also thought that this class of substrates will offer unique opportunity for asymmetric induction, as two‐points binding with chiral Lewis acids will become possible.…”

Section: Introductionmentioning

confidence: 99%

Formal Homo‐Nazarov and Other Cyclization Reactions of Activated Cyclopropanes

Simone

Saget

Benfatti

et al. 2011

Chemistry A European J

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Abstract:The Nazarov cyclization of divinyl ketones gives access to cyclopentenones. Replacing one of the vinyl groups by a cyclopropane leads to a formal homo-Nazarov process for the synthesis of cyclohexenones. In contrast to the Nazarov reaction, the cyclization of vinyl-cyclopropyl ketones is a stepwise process, often requiring harsh conditions. Herein, we describe two different approaches for further polarization of the threemembered ring of vinyl-cyclopropyl ketones in order to allow the formal homo-Nazarov reaction under mild catalytic conditions. In the first approach, the introduction of an ester group  to the carbonyl on the cyclopropane gave a more than tenfold increase in reaction rate, allowing us to extend the scope of the reaction to non electron-rich aryl donor substituents in  position to the carbonyl on the cyclopropane. In this case, a proof of principle for asymmetric induction could be achieved using chiral Lewis acid catalysts. In the second approach, heteroatoms, especially nitrogen, were introduced  to the carbonyl on the cyclopropane. In this case, the reaction was especially successful when the vinyl group was replaced by an indole heterocycle. With a free indole, the formal homo-Nazarov cyclization on the C3 position of indole was observed using a copper catalyst. In contrast, a new cyclization reaction on the N1 position was observed with Brønsted acid catalysts. Both reactions were applied to the synthesis of natural alkaloids. Preliminary investigations on the rationalization of the observed regioselectivity are also reported.

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A Catalytic Homo-Nazarov Cyclization Protocol for the Synthesis of Heteroaromatic Ring-Fused Cyclohexanones

Cited by 53 publications

References 31 publications

Ein neues goldenes Zeitalter in der Chemie Donor‐Akzeptor‐substituierter Cyclopropane

Ein neues goldenes Zeitalter in der Chemie Donor‐Akzeptor‐substituierter Cyclopropane

The Catalytic, Formal Homo‐Nazarov Cyclization as a Template for Diversity‐Oriented Synthesis

Formal Homo‐Nazarov and Other Cyclization Reactions of Activated Cyclopropanes

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