Synthesis of Substituted Naphthalenes via a Catalytic Ring-Expansion Rearrangement

The third generation designer amphiphile/surfactant, “Nok” (i.e., SPGS-550-M; β-sitosteryl polyoxoethanylsuccinate), soon to be commercially available from Aldrich, can be prepared in two steps using an abundant plant feedstock, β-sitosterol, together with succinic anhydride and PEG-550-M. Upon dissolution in water it forms nanomicelles that serve as nanoreactors, which can be characterized by both cryo-TEM and dynamic light scattering analyses. Several transition metal-catalyzed reactions have been run under micellar conditions to evaluate this surfactant relative to results obtained in nanoparticles composed of TPGS-750-M (i.e., a second generation surfactant). It is shown that Nok usually affords yields that are, in general, as good or better than those typically obtained with TPGS-750-M, and yet is far less costly.

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“…1 H NMR (400 MHz, CDCl 3 ) δ 8.14–8.06 (dd, J = 8.5, 0.5 Hz, 1H), 7.98–7.91 (dd, J = 8.3, 0.5 Hz, 1H), 7.63–7.32 (m, 8H), 2.77 (s, 3H). 31 …”

Section: Methodsmentioning

confidence: 99%

“Nok”: A Phytosterol-Based Amphiphile Enabling Transition-Metal-Catalyzed Couplings in Water at Room Temperature

2014

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“…Their catalytic ring expansion method involves the treatment of indenone with trimethylsilyldiazomethane in the presence of a palladium catalyst to afford the silylcyclopropanated intermediate. Reaction with an organometallic nucleophile affords the cyclopropylcarbinol which, under Lewis acidic conditions, undergoes ring expansion to regioselectively substituted naphthalenes 185. A carbon label would be most conveniently introduced via the indenone from either [ 14 C]acetic acid or [ 14 C]benzaldehyde rather than from trimethylsilyldiazomethane (Scheme ) 186…”

Section: Ring Expansionmentioning

confidence: 99%

Synthetic approaches to regiospecifically mono‐ and dilabelled arenes

Gregson

Herbert

Row

2011

Labelled Comp Radiopharmac

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A variety of methods for the preparation of selectively mono-, di-or tri-labelled arenes are reviewed. The review concentrates on those for which the application to labelled synthesis has been demonstrated. Further methods, the application of which to labelled synthesis appears viable but which have not been reduced to practise, are included also. The available methods provide a range of substitution patterns.

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“…Similar conditions have been used to remove silyl groups from cyclopropanes,b ut not cyclopropanones. [24] Ther esulting product was not, however, the desilylated cyclopropanone but instead unsaturated aldehyde 29.T his aldehyde was isolated in 51 %y ield from enyne 7,r epresenting an average 80 %y ield for each of the three steps.A ldehyde 29 results from cleavage of the cyclopropanone CÀCbond between the diisopropylsilyl group and the ketone.Notably,nointermediates were observed by TLC.…”

Section: Angewandte Chemiementioning

confidence: 96%

Enyne [4+4] Cycloaddition/Oxidation: Ring Contraction via Cyclopropanones and Their Anionic Ring‐Opening Reactions

2016

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Irradiation of a 1,3-enyne tethered to a 2-pyridone, in the presence of oxygen, leads to formation of a seven-membered ring product, an overall [4+4-1] reaction. This transformation involves two unstable intermediates and a sequence of unusual reactions. An initial [4+4] photocycloaddition of the enyne with the pyridone yields a 1,2,5-cyclooctatriene. Photooxidation of this triene forms a cyclopropanone and subsequent photoextrusion of carbon monoxide gives the observed 1,4-cycloheptadiene product. The first-formed cyclooctatriene and the cyclopropanone could be observed and characterized spectroscopically. The cyclopropanone underwent CO extrusion both photochemically and thermally to give the cycloheptadiene product. Addition of fluoride or acetylide to the most stable cyclopropanone occurred chemoselectively at the two different silicon groups rather than the carbonyl group. The resulting cyclopropanone ring openings gave unsaturated aldehydes.

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Synthesis of Substituted Naphthalenes via a Catalytic Ring-Expansion Rearrangement

Cited by 62 publications

References 23 publications

“Nok”: A Phytosterol-Based Amphiphile Enabling Transition-Metal-Catalyzed Couplings in Water at Room Temperature

“Nok”: A Phytosterol-Based Amphiphile Enabling Transition-Metal-Catalyzed Couplings in Water at Room Temperature

Synthetic approaches to regiospecifically mono‐ and dilabelled arenes

Enyne [4+4] Cycloaddition/Oxidation: Ring Contraction via Cyclopropanones and Their Anionic Ring‐Opening Reactions

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