Photochemical cycloadditions of benzonitrile to alkenes. Factors controlling the site of addition

Cantrell, Thomas S.

doi:10.1021/jo00862a014

Cited by 54 publications

(20 citation statements)

References 7 publications

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“…30 The attack of nucleophilic solvents on 'contact ion pairs' has been invoked previously to explain structural features of products resulting from the photoreactions of 2-phenyl-1-pyrrolinium ion with (prop-2-enyl)-cyclopropane or butadiene in methanol. 31 …”

Section: :1:1 Adducts Of Cyanonaphthalene Methanol and Norbornadienementioning

confidence: 99%

Stereospecific nucleophilic trapping of encounter complexes between photoexcited 1-cyanonaphthalene and norbornadiene

Weng

Roth

1998

J. Phys. Org. Chem.

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Photo-induced electron donor-acceptor reactions between 1-cyanonaphthalene (CNN) and norbornadiene (N) generate products of several structure types. Methanol adducts (1-3) formed in polar solvents are rationalized via the radical cation, N Á , and stereospecific (exo-) nucleophilic attack by methanol. In less polar solvents, CNN and N form [2 + 2]-cycloadducts, exclusively on the exo-face of N. In non-polar solvents containing methanol, CNN, N and methanol combine to form 1:1:1 adducts, containing the sensitizer on the endo-and the methoxy groups on the exo-face. The formation of these products is rationalized via the trapping of encounter complexes of different geometries. Any rearrangement of the norbornenyl system can be eliminated, since neither tricyclyl nor 7-methoxynorbornenyl structures are formed. Apparently, the alcohol captures an endo-encounter complex of CNN and N by attack from the exo-face, similar to the attack of methanol on N Á .

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Section: :1:1 Adducts Of Cyanonaphthalene Methanol and Norbornadienementioning

confidence: 99%

Stereospecific nucleophilic trapping of encounter complexes between photoexcited 1-cyanonaphthalene and norbornadiene

Weng

Roth

1998

J. Phys. Org. Chem.

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“…Ethenes having four alkyl substituents, two alkoxy, or two alkyl and one alkoxy, undergo photoaddition at the nitrile function leading to 2-azabutadienes 13 together with varying amounts of their azetine 14 precursor. (40) Other less electron-rich ethenes (14) undergo specific addition at the 1,2-positions of the phenyl ring. In contrast, irradiation of nitrobenzene and ethenes at room temperature gives a complex mixture of products, but at -70°C the unstable adduct 15 is formed.…”

Section: Arenes and Ethenesmentioning

confidence: 99%

Photoaddition and Photocyclization Processes of Aromatic Compounds

Gilbert

1984

Synthetic Organic Photochemistry

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“…The reaction was found to tolerate a range of aryl alkyne coupling partners, including terminal and internal aryl alkynes. Specifically, alkynes bearing functional groups such as esters (32), amides (34), ketones (31) and free alcohols (33) were all tolerated by the optimal reaction conditions to form the desired products in up to 86% yield. Notably, alkynes incorporating an additional activating group such as an aryl ring (24), ester (32), amide (34) or a ketone (31) were found to be higher yielding with yields up to 86%.…”

mentioning

confidence: 99%

“…Specifically, alkynes bearing functional groups such as esters (32), amides (34), ketones (31) and free alcohols (33) were all tolerated by the optimal reaction conditions to form the desired products in up to 86% yield. Notably, alkynes incorporating an additional activating group such as an aryl ring (24), ester (32), amide (34) or a ketone (31) were found to be higher yielding with yields up to 86%. Sterically demanding internal alkynes (30,(35)(36) were amenable to the reaction conditions, albeit resulting in decreased yields.…”

mentioning

confidence: 99%

1- and 2-Azetines via Visible Light-Mediated [2+2]-Cycloadditions of Alkynes and Oximes

Schindler

Wearing

Blackmun

et al. 2021

Preprint

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Azetines, four-membered unsaturated nitrogen-containing heterocycles, hold great potential for drug design and development, but remain underexplored due to challenges associated with their synthesis. We report an efficient, visible light-mediated approach towards 1-and 2-azetines relying on alkynes and the unique triplet state reactivity of oximes, specifically 2-isoxazolines. While 2-azetine products are accessible upon intermolecular [2+2]-cycloaddition via triplet energy transfer from a commercially available iridium photocatalyst, the selective formation of 1-azetines proceeds upon a second, consecutive, energy transfer process. Mechanistic studies are consistent with a stepwise reaction mechanism via N-O bond homolysis following the second energy transfer event to result in the formation of 1-azetine products. Characteristic for this method is its operational simplicity, mild conditions and modular approach that allows for the synthesis of functionalized azetines and tetrahydrofurans via in situ hydrolysis from readily available precursors.

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Photochemical cycloadditions of benzonitrile to alkenes. Factors controlling the site of addition

Cited by 54 publications

References 7 publications

Stereospecific nucleophilic trapping of encounter complexes between photoexcited 1-cyanonaphthalene and norbornadiene

Stereospecific nucleophilic trapping of encounter complexes between photoexcited 1-cyanonaphthalene and norbornadiene

Photoaddition and Photocyclization Processes of Aromatic Compounds

1- and 2-Azetines via Visible Light-Mediated [2+2]-Cycloadditions of Alkynes and Oximes

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