Photochemical Arylation of Alkenols: Role of Intermediates and Synthetic Significance

Protti, Stefano; Dondi, Daniele; Fagnoni, Maurizio; Albini, Angelo

doi:10.1002/ejoc.200701177

Cited by 25 publications

(8 citation statements)

References 51 publications

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“…The first‐formed triplet adduct cation with alkenes has a diradical character ( V ), just like the starting phenyl cation, but then intersystem crossing occurs to the more stable singlet phenethyl cation/phenonium ion system ( I / III ), which, contrary to what happens in the triplet manifold, undergoes addition of nucleophiles. The multiplicity‐dependent selectivity has been exploited in some three‐component photoarylations [15,17a–17c,18a] (Scheme , c) and in the intramolecular version when the trap bears two nucleophilic sites, as is the case with ω‐alkenols19 and ω‐alkenoic acids 20. Whatever the mode of generation, the phenonium may be involved competitively in various processes (nucleophile addition, deprotonation and rearrangement).…”

Section: Introductionmentioning

confidence: 99%

Looking for a Paradigm for the Reactivity of Phenonium Ions

Protti¹,

Dondi²,

Mella³

et al. 2011

Eur J Org Chem

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The addition of a photogenerated phenyl cation to an alkene offers an entry, under mild conditions, to the phenethyl cation/phenonium ion system in organic solvents. Taking advantage of this, a product study has been carried out in parallel with a computational characterization of the intermediates. Thus, 4-methoxy-and 4-dimethyaminophenyl cations have been photogenerated from the corresponding chlorobenzenes in the presence of mono-to tetrasubstituted olefins in polar or protic media. The chemistry that occurs has been correlated with the degree of anchimeric assistance offered by the phenyl group, as predicted by calculations. Two limiting situations arise, the first one when starting from monoor 1,2-disubstituted alkenes. In these cases, calculations evidence a large stabilization of the intermediate (phenonium

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Section: Introductionmentioning

confidence: 99%

Looking for a Paradigm for the Reactivity of Phenonium Ions

Protti¹,

Dondi²,

Mella³

et al. 2011

Eur J Org Chem

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“…Significant effort in this field has resulted in the synthesis of diverse oxygen heterocycle products with predictable regio-and diastereoselectivity. [3][4][5][6][7][8][9][10][11][12] While the related synthesis of enantiomerically enriched nitrogen heterocycles by either palladium-or copper-catalyzed enantioselective alkene carboamination methodologies has been substantially developed in recent years, [13,14] advances in reaction technology for catalytic enantioselective carboetherification/cyclization of unactivated alkenes have largely remained elusive. [15] Notable exceptions include palladium-catalyzed reactions of ortho-vinyl phenols, reactions which proceed through quinone methide intermediates, [16] and palladium-catalyzed cyclizations of g-and dunsaturated phenols which terminate in carbonylation or olefin insertion (whose substituted intermediates are unable to undergo b-hydride elimination).…”

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confidence: 99%

Enantioselective Copper‐Catalyzed Carboetherification of Unactivated Alkenes

et al. 2014

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Chiral saturated oxygen heterocycles are important components of bioactive compounds. Cyclization of alcohols onto pendant alkenes is a direct route to their synthesis, but few catalytic enantioselective methods enabling cyclization onto unactivated alkenes exist. Herein is reported a highly efficient copper-catalyzed cyclization of γ-unsaturated pentenols that terminates in C-C bond formation, a net alkene carboetherification. Both intra- and intermolecular C-C bond formations are demonstrated, yielding functionalized chiral tetrahydrofurans as well as fused-ring and bridged-ring oxabicyclic products. Transition state calculations support a cis-oxycupration stereochemistry-determining step.

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“…Analogously, when the carboxylic acid was changed into a hydroxy group, the corresponding cyclic ether could be obtained. 172 Scheme 89 Photo-promoted coupling of electron-rich aryl halides with potassium cyanide Scheme 90 Photo-promoted coupling of electron-rich aryl halides with functionalized olefins In 2006, Rossi and co-workers reported the synthesis of the aporphine and homoaporphine alkaloids (Scheme 91). 173 The key step is an intramolecular ortho-arylation of phenols with aryl halides in liquid ammonia promoted by light irradiation.…”

Section: Account Syn Lettmentioning

confidence: 99%

Recent Synthetic Applications of Catalyst-Free Photochemistry

Liu¹,

Li²

2017

Synlett

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Catalyst-free photochemistry provides numerous opportunities toward sustainable synthesis because catalyst separation can usually be avoided, which is consistent with green chemistry principles. Complementary to the well-reviewed photoredox chemistry, this review specifically summarizes the synthetic applications of photochemistry without external catalysts reported since 2000. The selected examples include both natural product synthesis and new methodology development. This review is arranged based on the type of chromophore. It is our hope that this review will inspire more synthetic chemists to embrace photochemistry into their research plans.1 Introduction2 Photochemistry of Olefins2.1 [2+2] Cycloaddition of Enones and Olefins2.2 Cycloaddition of Olefins without Carbonyl Groups2.3 Z/E Isomerization2.4 Cyclization2.5 Others3 Photochemistry of C=O3.1 The Paternò–Büchi Reaction3.2 The Yang Photoenolization3.3 The Norrish Type I Reaction3.4 The Norrish Type II Reaction3.5 Others4 Photochemistry of Nitrogen-Containing Functional Groups5 Photochemistry of Halogen-Containing Compounds6 Conclusion and Outlook

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Photochemical Arylation of Alkenols: Role of Intermediates and Synthetic Significance

Cited by 25 publications

References 51 publications

Looking for a Paradigm for the Reactivity of Phenonium Ions

Looking for a Paradigm for the Reactivity of Phenonium Ions

Enantioselective Copper‐Catalyzed Carboetherification of Unactivated Alkenes

Recent Synthetic Applications of Catalyst-Free Photochemistry

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