Organoboron Reagent-Controlled Selective (Deutero)Hydrodefluorination.

(Deuterium-labeled) CF2 H- and CFH2 -moieties are of high interest in drug discovery. The high demand for the incorporation of these fluoroalkyl moieties into molecular structures has witnessed significant synthetic progress, particularly in the (deutero)hydrodefluorination of CF3 -containing compounds. However, the controllable replacement of fluorine atoms while maintaining high chemoselectivity remains challenging. Herein, we describe the development of a selective (deutero)hydrodefluorination reaction via electrolysis. The reaction exhibits a remarkable chemoselectivity control, which is enabled by the addition of different organoboron sources. The procedure is operationally simple and scalable, and provides access in one step to high-value building blocks for application in medicinal chemistry. Furthermore, density functional theory (DFT) calculations have been carried out to investigate the reaction mechanism and to rationalize the chemoselectivity observed.

Cascade cyclization for the synthesis of indolo[2,1-α]isoquinoline derivatives via visible-light-induced halogen-atom-transfer (XAT) and hydrogen-atom-transfer (HAT).

A transition metal-free photoredox cascade cyclization is herein reported. In this protocol, sustainable visible light was used as the energy source and organic light-emitting molecule eosin Y served as an efficient photocatalyst. A variety of easily available 2-aryl-N-acryloyl indoles can readily react with alkyl radicals, which are generated from organohalides and tertiary amines via either the halogen-atom-transfer (XAT) or the hydrogen-atom-transfer (HAT) process, furnishing the desired indolo[2,1-α]isoquinoline derivatives in good to moderate yields. This protocol features broad substrate scope and good functional group tolerance under mild conditions.

Copper/silver co-mediated three-component bicyclization for accessing indeno[1,2-c]azepine-3,6-diones.

A new copper/silver-co-mediated three-component bicyclization of benzene-linked 1,6-enynes with ICF2CO2Et with TMSN3 was reported, and used to produce a wide range of hitherto unreported difluorinated tetrahydroindeno[1,2-c]azepine-3,6-diones with moderate to good yields. The mechanistic pathway consists of radical-induced 1,6-addition-cyclization, oxidative addition, reductive elimination, nitrene insertion and N-O cleavage, resulting in continuous multiple bond-forming events including C-C and C-N bonds to build up a 6/5/7 tricyclic framework.

Visible-light photocatalytic bicyclization of ß-alkynyl propenones for accessing diastereoenriched syn-fluoren-9-ones.

A novel visible-light photocatalytic bicyclization of ß-alkynyl propenones with α-bromocarbonyls for highly diastereoselective synthesis of richly decorated syn-fluoren-9-ones is described. The reaction proceeds via a radical-triggered 5-exo-dig cyclization/1,6-H-abstraction/6-endo-trig cyclization cascade and offers a new and practical method for the assembly of 6/5/6 carbocyclic skeletons via C(sp3)-H alkenylation.

Stereoselective synthesis of sulfonated 1-indenones via radical-triggered multi-component cyclization of ß-alkynyl propenones.

New radical-triggered multi-component cyclizations of ß-alkynyl propenones have been developed, leading to 50 examples of sulfonated 1-indenones with generally good yields and high levels of stereoselectivity. The oxidant-free azosulfonylation of ß-alkynyl propenones with aryldiazonium salts and DABSO was realized under the neutral-redox conditions where TBHP enabled the direct selenosulfonylation of ß-alkynyl propenones by combining sulfinic acids and diphenyl diselenide. This protocol features a broad substrate scope, high functional group tolerance and mild reaction conditions.