Carbenes from cyclopropanated aromatics

Roth, Alexander D.; Thamattoor, Dasan M.

doi:10.1039/d3ob01525d

“…In an effort to develop alternative photochemical precursors to allenylidenes with a potential for general applicability, we modified our cyclopropanated phenanthrene system (33), from which our laboratory has previously generated several cyclic and acyclic alkylidenecarbenes (34), 26 to incorporate an allene unit at the corner of the cyclopropane ring (35a, b, and c), as shown in Scheme 7. Herein, we describe our synthetic approach to 35a, b, and c, their subsequent photolysis leading to the extrusion of 1, 36a, and 36b respectively, and trapping studies.…”

Section: Introductionmentioning

confidence: 99%

Photochemical Generation of Allenylidenes from Cyclopropanated Phenanthrenes: An Experimental and Computational Study

Roth,

Ramgren,

Wen

et al. 2024

J. Org. Chem.

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To address the scarcity of generally applicable photochemical routes to allenylidenes in solution, phenanthrene-based sources have been investigated. Specifically, the syntheses of 1-vinylidene-1a,9b-dihydro-1H-cyclopropa[l]phenanthrene, 1-(2-phenylvinylidene)-1a,9b-dihydro-1H-cyclopropa[l]phenanthrene, and 1-(2-methylvinylidene)-1a,9b-dihydro-1H-cyclopropa[l]phenanthrene, photochemical precursors to propadienylidene, 3-phenylpropadienylidene, and 3-methylpropadienylidene have been carried out. Photolysis of these new precursors in olefin traps and benzene afforded the expected cyclopropane adducts of the corresponding allenylidenes. Quantum chemical calculations show that the ground state of all three carbenes is a singlet with a singlet–triplet gap of ∼29, 30, and 33 kcal/mol for propadienylidene, 3-phenylpropadienylidene, and 3-methylpropadienylidene, respectively.

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Aromative Dephosphinidenation of a Bisphosphirane‐Fused Anthracene toward E−H (E=H, Si, N and P) Bond Activation

Luo,

Liu,

Huang

et al. 2024

Angewandte Chemie

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A bisphosphirane‐fused anthracene (5) was prepared by treatment of a sterically encumbered amino phosphorus dichloride (3) with MgA•3THF (A = anthracene). X‐ray diffraction analysis revealed a pentacyclic framework consisting of 5 with two phosphirane rings fused to the anthracene in a trans‐fashion. Compound 5 has been shown to be an efficient phosphinidene synthon, readily liberating two transient phosphinidene units for subsequent downstream bond activation via the reductive elimination of anthracene under mild conditions. The formal oxidative addition of H2 and E‐H (E = Si, N, P) bonds by the liberated phosphinidene provided diphosphine and substituted phosphines. Furthermore, phosphinidene transfer to alkenes and alkynes smoothly yielded the corresponding phosphiranes and phosphirenes. The mechanism of the H2 activation by 5 was investigated by density functional theory (DFT) calculations.

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Aromative Dephosphinidenation of a Bisphosphirane‐Fused Anthracene toward E−H (E=H, Si, N and P) Bond Activation

Luo,

Liu,

Huang

et al. 2024

Angew Chem Int Ed

0

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A bisphosphirane‐fused anthracene (5) was prepared by treatment of a sterically encumbered amino phosphorus dichloride (3) with MgA•3THF (A = anthracene). X‐ray diffraction analysis revealed a pentacyclic framework consisting of 5 with two phosphirane rings fused to the anthracene in a trans‐fashion. Compound 5 has been shown to be an efficient phosphinidene synthon, readily liberating two transient phosphinidene units for subsequent downstream bond activation via the reductive elimination of anthracene under mild conditions. The formal oxidative addition of H2 and E‐H (E = Si, N, P) bonds by the liberated phosphinidene provided diphosphine and substituted phosphines. Furthermore, phosphinidene transfer to alkenes and alkynes smoothly yielded the corresponding phosphiranes and phosphirenes. The mechanism of the H2 activation by 5 was investigated by density functional theory (DFT) calculations.

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Carbenes from cyclopropanated aromatics

Abstract: Although a ripe old discipline by now, carbene chemistry continues to flourish as both theorists and experimentalists have shown sustained interest in this area of research. While there are numerous...

Cited by 4 publications

References 91 publications

Photochemical Generation of Allenylidenes from Cyclopropanated Phenanthrenes: An Experimental and Computational Study

Photochemical Generation of Allenylidenes from Cyclopropanated Phenanthrenes: An Experimental and Computational Study

Aromative Dephosphinidenation of a Bisphosphirane‐Fused Anthracene toward E−H (E=H, Si, N and P) Bond Activation

Aromative Dephosphinidenation of a Bisphosphirane‐Fused Anthracene toward E−H (E=H, Si, N and P) Bond Activation

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