Photochemical Carbene Transfer Reactions of Aryl/Aryl Diazoalkanes—Experiment and Theory**

Angewandte Chemie International Edition, Journal Year: 2021, Volume and Issue: 60(24), P. 13271 - 13279

Published: March 9, 2021

Controlling the reactivity of carbene intermediates is a key parameter in development selective transfer reactions and usually achieved by metal complexes via singlet metal-carbene intermediates. In this combined experimental computational studies, we show that free diaryl carbenes can be controlled electronic properties substituents without need external additives. The introduction electron-donating -withdrawing groups results significant perturbation triplet energy splitting intermediate activation energies consecutive reactions. This strategy now overcomes long-standing paradigm allows realization highly chemoselective with alkynes. We could readily accessed photolysis corresponding diazo compounds these undergo cyclopropenation, cascade, or C-H functionalization Experimental theoretical mechanistic analyses confirm participation different spin states rationalize for observed reactivity.

Language: Английский

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Visible light mediated, metal-free carbene transfer reactions of diazoalkanes with propargylic alcohols

Chemical Communications, Journal Year: 2019, Volume and Issue: 55(33), P. 4881 - 4884

Published: Jan. 1, 2019

The photolysis of donor–acceptor diazoalkanes in the presence propargylic alcohols furnishes valuable, sterically demanding tetra-substituted cyclopropenes high yield under metal-free conditions.

Language: Английский

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Photochemical, Metal‐Free Sigmatropic Rearrangement Reactions of Sulfur Ylides

Chemistry - A European Journal, Journal Year: 2019, Volume and Issue: 25(27), P. 6703 - 6706

Published: March 28, 2019

Abstract Sigmatropic rearrangement reactions constitute one of the most fundamental carbenes. While state‐of‐the‐art synthetic methods require use expensive precious metal catalysts, application visible light for photolysis α‐aryldiazoacetates is much less investigated and provides an operationally simple entry to carbenes under mild reaction conditions. Herein, we report on blue‐light induced sigmatropic sulfur compounds with α‐aryldiazoacetates. This process, depending substitution pattern sulfide, opens up formal insertion into S−N, S−C, or C−H bonds.

Language: Английский

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Blue Light‐Promoted N−H Insertion of Carbazoles, Pyrazoles and 1,2,3‐Triazoles into Aryldiazoacetates

Advanced Synthesis & Catalysis, Journal Year: 2019, Volume and Issue: 362(5), P. 1106 - 1111

Published: Dec. 23, 2019

Abstract Blue light irradiation of aryldiazoacetates leads to the formation free carbenes, which can react with carbazoles, pyrazoles and 1,2,3‐triazoles afford corresponding N−H inserted products. These reactions are performed under air at room temperature, allowing mild preparation a variety motifs found in biologically relevant targets. magnified image

Language: Английский

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Stoichiometric Photochemical Carbene Transfer by Bamford–Stevens Reaction

Chemistry - A European Journal, Journal Year: 2019, Volume and Issue: 26(12), P. 2586 - 2591

Published: Dec. 11, 2019

The photolysis of diazoalkanes is a timely strategy to conduct carbene-transfer reactions under mild and metal-free reaction conditions, has developed as an important alternative conventional metal-catalyzed reactions. One the major limitations lies within rapidly occurring side carbene intermediate with remaining diazoalkane molecules that result in use excess partner thus impacts on efficiency. Herein, we describe protocol takes advantage situ generation donor-acceptor by Bamford-Stevens reaction. Following this strategy, concentration can be minimized reduce unwanted now photochemical transfer stoichiometric conditions. We have explored approach C-H N-H functionalization cyclopropanation N-heterocycles could demonstrate applicability method 51 examples.

Language: Английский

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