Micellar photocatalysis enables divergent C-H arylation and N dealkylation of benzamides via N-acyliminium cations

Micellar photocatalysis has recently opened new avenues to activate strong carbon halide bonds. So far, however, it has mainly explored strongly reducing conditions restricting the available chemical space to radical or anionic reactivity. Here, we demonstrate a radical-polar crossover process involving cationic intermediates, which enables chemodivergent modification of chlorinated benzamide derivatives via either C H arylation or N dealkylation. The catalytic system operates under mild conditions employing methylene blue as a photocatalyst and blue LEDs as the light source. Factors determining the reactivity of substrates and preliminary mechanistic studies are presented.

Recent Advances in Visible-Light-Mediated Amide Synthesis

Visible-light photoredox catalysis has attracted tremendous interest within the synthetic community. As such, the activation mode potentially provides a more sustainable and efficient platform for the activation of organic molecules, enabling the invention of many controlled radical-involved reactions under mild conditions. In this context, amide synthesis via the strategy of photoredox catalysis has received growing interest due to the ubiquitous presence of this structural motif in numerous natural products, pharmaceuticals and functionalized materials. Employing this strategy, a wide variety of amides can be prepared effectively from halides, arenes and even alkanes under irradiation of visible light. These methods provide a robust alternative to well-established strategies for amide synthesis that involve condensation between a carboxylic acid and amine mediated by a stoichiometric activating agent. In this review, the representative progresses made on the synthesis of amides through visible light-mediated radical reactions are summarized.

Radical Addition of Hydroxy Quinazolines and Alkylation of Quinones via the Electro-induced Homolysis of 4-Alkyl-1,4-dihydropyridines

Herein, we report the formation of C(sp3)-centered radicals via the electro-induced homolysis of 4-alkyl-1,4-dihydropyridines (alkyl-DHPs). The resulting alkyl radicals reacted with hydroxy quinazolines or quinones to afford 2-alkyl dihydroquinazolinones or alkylated quinones. A broad range of alkyl DHPs could be used as versatile radical precursors under electrolysis conditions. This alterative strategy provided a simple and effective pathway for the construction of C(sp2)–C(sp3) and C(sp3)–C(sp3) bonds under mild conditions.

Silyl formates as hydrosilane surrogates for the transfer hydrosilylation of ketones

An energetically and atom economic transfer hydrosilylation of ketones employing silyl formates as hydrosilanes surrogates under mild conditions is presented. A total of 24 examples of ketones have been successfully converted to their corresponding silyl ethers with 61-99% yield in the presence of a PNHP-based ruthenium catalyst and silyl formate reagent. The crucial role of the ligand for the transformation is demonstrated.

Synthesis of Isoquinoline-1,3(2H,4H)-diones by Visible-light-mediated the Cyclization of Acryloylbenzamides with Alkyl Boronic Acids, Arylsulfonylhydrazides and Oxime Esters

An efficient visible-light-mediated tandem reaction of acryloylbenzamides with alkyl boronic acids, arylsulfonylhydrazides and oxime esters is developed. The reaction proceeds the radical addition and cyclization to give various isoquinoline-1,3(2H,4H)-diones in satisfactory yields under mild conditions, which provides a good opportunity to discover new meaningful bioactive compounds.