Synthesis of 4-cyanoethylated benzoxazines by visible-light-promoted radical oxycyanomethylation of olefinic amides with bromoacetonitrile

Visible-light-mediated selenocyclization of o-vinylanilides with diselenides

Herein, we describe a visible-light-mediated selenocyclization of o-vinylanilides with diselenides, which provides a mild and effective method for the synthesis of selenylated 4H-3,1-benzoxazines. This reaction proceeds under metal-free conditions, without the need for a chemical oxidant or a controlled O2 atmosphere and shows a broad substrate scope with yields of up to 98%. Additionally, the process is easily scalable to the gram scale.

Visible-light-promoted azidation/arylation of unactivated alkenes with Togni-N3via electron donor-acceptor complexes

A visible-light-promoted azidation/arylation of unactivated alkenes with Togni-N3 has been achieved, leading to a series of azidated pyrrolo[1,2-a]indoles under photocatalyst-free conditions. Notably, an EDA complex derived from the electron-rich indole derivatives and Togni-N3 served as the key intermediate in this reaction.

Photoinduced Tandem Cyanomethylation/Cyclization of Unsaturated Compounds: Access to Cyanomethylated 7- or 5-Membered N-Heterocycles

A cyanomethylation/cyclization of aryl acetylenes/ethylenes with bromoacetonitrile was finished in a photopromoted condition, which offers an efficient and mild protocol for the preparation of cyanomethylated 7- or 5-membered N-heterocycles with good yields. Meanwhile, trichloroacetonitrile was also compatible with this radical pathway. In addition, a variety of single-crystal X-ray diffraction measurements, scaled-up operations to 1 mmol, functional group transformations of final products, light on/off experiments, and even radial inhibition studies were smoothly performed in this tandem system.

Visible-Light-Promoted Direct C3-H Cyanomethylation of 2H-Indazoles

The efficient visible-light-promoted cyanomethylation of 2H-indazoles in the presence of Ir(ppy)₃ as the photocatalyst and bromoacetonitrile as the cyanomethyl radical source was achieved under mild conditions, providing a series of C3-cyanomethylated derivatives in good yields.

Electrochemical Thiocyanation/Cyclization Cascade to Access Thiocyanato-Containing Benzoxazines

Due to the importance of SCN-containing heteroarenes, developing novel and green synthetic protocols for the synthesis of SCN-containing compounds has drawn much attention over the last decades. We reported here an electrochemical oxidative cyclization of ortho-vinyl aniline to access various SCN-containing benzoxazines. Mild conditions, an extra catalyst-free and oxidant-free system, and good tolerance for air highlight the application potential of this method.

Photomediated Tandem Sulfonyl Addition-Chemoselective N-Cyclization of o-Alkenyl Aryl Ureas: Direct Assembly of Functionalized Dihydroquinazolinones

Photoredox-mediated tandem addition-chemoselective cyclization of o-alkenyl aryl ureas is reported for the synthesis of sulfonyl and activated alkyl-decorated dihydroquinazolinones. By a careful choice of o-alkenyl aryl urea starting materials, we achieved chemoselective N-cyclization in the presence of more reactive amidic oxygen. We have demonstrated the scope of the methodology with a variety of sulfonyl chlorides and activated alkyl halides. Finally, large-scale synthesis of sulfonyl-substituted dihydroquinazolinone showcases the synthetic utility of the methodology.

Copper-Catalyzed Bromo-cyanomethylative Cyclization of Enynes

A copper-catalyzed bromo-cyanomethylative cyclization of 1,6-enynes is demonstrated. The treatment of 2-bromoacetonitrile with CuI enables the alkyl radical generation and triggers the radical addition/cyclization/bromination sequence, giving various vinyl C-Br bonds containing functionalized heterocycles in good yields.

Photoredox catalyzed cascade CF3 addition/chemodivergent annulations of ortho-alkenyl aryl ureas

Herein, we report a substrate-controlled cascade cyclization of o-alkenyl aryl ureas, an ambident nucleophile for constructing functionalized heterocycles such as 2-amino-1,3-benzoxazines and dihydroquinazolinones in a chemodivergent fashion using photoredox catalysis under mild conditions. The versatility of the method has been successfully demonstrated by applying this strategy to a wide range of substrates and for the synthesis of functionalized etifoxine drug derivatives.

Cyanoalkylation/alkynylation of allylic alcohol through intramolecular radical 1,2-alkynyl migration

A di-tert-butyl peroxide (DTBP)-promoted difunctionalization of α-aryl α-alkynyl allylic alcohols with alkyl nitriles was developed, affording a series of α-alkynyl γ-cyano functionalized ketones in moderate yields. This procedure involved C(sp³)-H bond cleavage of alkyl nitriles and radical 3-exo-dig cyclization. After this, radical 1,2-alkynyl migration is preferred rather than 1,2-aryl migration.