Methylenation of [2.2]Paracyclophane‐1,9‐diene and [2.2]Paracyclophane

Näder, Reinhard; Meijere, Armin de

doi:10.1002/anie.197601661

Cited by 9 publications

(2 citation statements)

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“…In no instance was the C(sp 3 )–H functionalization product observed. As previously seen in the reaction with diazomethane, , 3aa derived from cyclopropanation of the C2–C3 bond preferentially exists in the cycloheptatriene conformer, whereas 4aa derived from cyclopropanation of the C1–C2 bond preferentially exists in the norcaradiene conformer. The reason for the change in the cycloheptatriene/norcaradiene ratio is likely due to the influence of hybridization [C(sp 2 ) versus C(sp 3 )] on the strain associated with the paracyclophanes.…”

Section: Resultssupporting

confidence: 64%

“…In this study, we examined whether the enantioselective reaction of donor/acceptor carbenes with paracyclophanes would result in the ready generation of novel paracyclophane derivatives. Previous studies on the reaction of [2.2]paracyclophane with diazomethane resulted in the formation of a mixture of mono-, di-, tri-, and polysubstituted derivatives, including two regioisomeric monosubstituted products in undefined yields (Scheme C). , The only effective carbene example of C–H functionalization involved an intramolecular process that required considerable effort to generate the carbene precursor . The plan here was to use rhodium-stabilized donor/acceptor carbenes as the reactive intermediates in intermolecular reactions and use catalysts to control the reaction outcome (Scheme D).…”

Section: Introductionmentioning

confidence: 99%

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Rhodium(II)-Catalyzed Asymmetric Cyclopropanation and Desymmetrization of [2.2]Paracyclophanes

Ly,

Bacsa,

Davies

2024

ACS Catal.

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Chiral [2.2]paracyclophane derivatives are of considerable interest because of their potential in asymmetric catalysis and the development of chiral materials. This study describes the scope of rhodium-catalyzed reactions of aryldiazoacetates with [2.2]paracyclophanes. The reaction with the parent [2.2]paracyclophane resulted in cyclopropanation at two positions, the ratio of which is catalyst-controlled. Because of the strain in the system, one of the cyclopropanes exists primarily as the norcaradiene structure, whereas the other preferentially exists as the cycloheptatriene conformer. In contrast, the reaction with [3.3]paracyclophane results in benzylic C−H functionalization. The reactions with substituted [2.2]paracyclophanes using chiral catalysts can result in either kinetic resolution or desymmetrization. The Rh 2 (S-p-PhTPCP)] 4 -catalyzed reaction of monosubstituted paracyclophanes results in kinetic resolution with a selectivity (s) factor of up to 20, whereas reactions on C 2v -symmetric disubstituted [2.2]paracyclophanes with Rh 2 (S-TPPTTL) 4 [TPPTTL = 2-(1,3-dioxo-4,5,6,7-tetraphenylisoindolin-2-yl)-3,3-dimethylbutanoate] results in effective desymmetrization to form cycloheptatriene-incorporated paracyclophanes in 78−98% ee.

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Section: Resultssupporting

confidence: 64%

Section: Introductionmentioning

confidence: 99%

Rhodium(II)-Catalyzed Asymmetric Cyclopropanation and Desymmetrization of [2.2]Paracyclophanes

Ly,

Bacsa,

Davies

2024

ACS Catal.

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Chemisches Verhalten mehrfach überbrückter [2_n]Cyclophane

Kleinschroth

Hopf

1982

Angewandte Chemie

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Professor Klaus Weissermel zum 60. Geburtstag gewidmetMehrfach uberbriickte [2.]Cyclophane bilden eine neuartige Klasse aromatischer Verbindungen, in denen zwei Benzolringe durch drei bis maximal sechs Ethanobriicken miteinander verknupft sind. Herausragende, sie von den klassischen nichtanellierten Arenen unterscheidende chemische Eigenschaft ist die Reaktivitat bezuglich Additionen; beispielsweise reagieren insbesondere einige der hoher uberbriickten Homologen leicht in Diels-Alder-Additionen, Hydrierungen und ionischen Additionen. Das regenerative Verhalten aromatischer Molekule ist jedoch in den [2,]Cyclophanen nicht vollstandig zuruckgedrangt; so sind typische elektrophile aromatische Substitutionsreaktionen wie die Bromierung, die Friedel-Crafts-Acylierung und die Nitrierung moglich. AuRer diesen unter Aufhebung bzw. Erhaltung der Benzolringe ablaufenden Prozessen wurden Reaktionen an und mit den Ethanobriicken, z. B. deren Spaltung und Funktionalisierung, beobachtet. SchlieRlich konnen bei [2,]Cyclophanen auch lsomerisierungen auftreten.

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