Zejiang Li

Copper- and Iron-Catalyzed Decarboxylative Tri- and Difluoromethylation of α,β-Unsaturated Carboxylic Acids with CF3SO2Na and (CF2HSO2)2Zn via a Radical Process

A copper-catalyzed decarboxylative trifluoromethylation of various α,β-unsaturated carboxylic acids by using a stable and inexpensive solid, sodium trifluoromethanesulfinate (CF(3)SO(2)Na, Langlois reagent), was developed. In addition, an iron-catalyzed difluoromethylation of aryl-substituted acrylic acids by using zinc difluoromethanesulfinate (DFMS, (CF(2)HSO(2))(2)Zn, Baran reagent) via a similar radical process was also achieved.

Free-Radical Cascade Alkylarylation of Alkenes with Simple Alkanes: Highly Efficient Access to Oxindoles via Selective (sp3)C–H and (sp2)C–H Bond Functionalization

A copper-catalyzed alkylarylation of alkenes with simple alkanes was achieved, which not only provided an efficient method to prepare various alkyl-substituted oxindoles, but also represented a novel strategy for selective sp(3) C-H functionalization/C-C bond formation via a free-radical cascade process. Additionally, selective activation of unactivated (sp(3))C-H and (sp(2))C-H bonds by one single step is achieved in this system, which would also provide a novel strategy for raising efficiency in C-H bond functionalization.

A Free Radical Cascade Cyclization of Isocyanides with Simple Alkanes and Alcohols

A copper-catalyzed free-radical cascade cyclization of isocyanides with simple alkanes and alcohols was developed, which allowed convenient access to various alkyl-substituted phenanthridines.

A Free-Radical Cascade Trifluoromethylation/Cyclization of N-Arylmethacrylamides and Enynes with Sodium Trifluoromethanesulfinate and Iodine Pentoxide

An I(2)O(5)-promoted free-radical cascade trifluoromethylation/cyclization of a broad range of N-arylmethacrylamides and enynes with sodium trifluoromethanesulfinate in aqueous medium has been achieved. This strategy allows highly selective access to a variety of CF(3)-containing oxindoles and pyrrolidines. Electron spin resonance (ESR) studies indicate that atom-transfer processes are involved in this system.

Iodotrifluoromethylation of Alkenes and Alkynes with Sodium Trifluoromethanesulfinate and Iodine Pentoxide

A scalable, selective, and operationally easy iodotrifluoromethylation of a wide range of alkenes and alkynes by using two simple and safe solids, sodium trifluoromethanesulfinate and iodine pentoxide, in aqueous medium has been developed. Mechanistic studies confirm that free-radical processes are involved in this system since the key radical intermediates such as CF(3) and β-CF(3) alkyl radicals have been clearly detected by spin trapping and electron spin resonance.

Pd-Catalyzed Olefination of Furans and Thiophenes with Allyl Esters

A direct Pd(II)-catalyzed olefination of furans and thiophenes with allyl esters is demonstrated. Under the typical conditions, the dehydrogenative Heck coupling reactions of heteroarenes with allylic esters proceeded via a β-H elimination rather than a β-OAc elimination to give the corresponding γ-substituted allylic esters.

Pd-Catalyzed Olefination of Perfluoroarenes with Allyl Esters

An efficient Pd(II)-catalyzed direct olefination of perfluoroarenes with allyl esters is demonstrated. Under the typical conditions, the coupling reaction of fluorinated-arenes with allylic esters proceeded via a β-H elimination rather than a β-OAc elimination to give the corresponding γ-substituted allylic esters.

Pd(II)-Catalyzed Dehydrogenative Olefination of Vinylic C-H Bonds with Allylic Esters: General and Selective Access to Linear 1,3-Butadienes

This work demonstrates a general and efficient method to prepare conjugated dienes by Pd(II)-catalyzed direct olefination of unactivated alkenes with allylic esters and acrylates via vinylic C-H activation. Various aryl and heteroaryl alkenes as well as aliphatic alkenes all give the desired linear 1,3-butadienes with retention of the traditional leaving groups such as OAc and other carboxylic acid ester groups.

Iron-Catalyzed Stereospecific Olefin Synthesis by Direct Coupling of Alcohols and Alkenes with Alcohols

An efficient Fe(III)-catalyzed direct coupling of alkenes with alcohols and cross-coupling of alcohols with alcohols to give the corresponding substituted (E)-alkenes stereospecifically is demonstrated. Additionally, this reaction could be scaled up. The kinetic isotope effect (KIE) experiments indicated a typical secondary isotope effect in this process. Although benzylic alcohols were effective substrates, mild conditions, atom efficiency, environmental soundness, and stereospecificity are features that make this procedure very attractive.

A silver-initiated free-radical intermolecular hydrophosphinylation of unactivated alkenes

A scalable, operationally easy intermolecular hydrophosphinylation of various unactivated alkenes with H–P(O) compounds via an Ag(I)-initiated free radical process was developed. Mechanistic studies including electron-spin-resonance (ESR) and radical clock experiments suggest that atom transfer processes were involved in this system.