Photoredox radical/polar crossover enables C–H gem-difunctionalization of 1,3-benzodioxoles for the synthesis of monofluorocyclohexenes

Abstract

A photocatalytic C-H gem-difunctionalization of 1,3-benzodioxoles with two different alkenes for the synthesis of highly functionalized monofluorocyclohexenes is desribed. Using 4CzIPN as the photocatalyst, the direct single electron oxidation of...

Photoinduced synthesis of C2-linked phosphine oxides via radical difunctionalization of acetylene

“…Based on the above results and also considering the related literature reports, 12 a ,15 c ,16,19 a plausible reaction mechanism is proposed for the present transformations (Scheme 5). First, a phosphinoyl radical ( B ) is produced via proton-coupled electron transfer (PCET) oxidation in the presence of K 2 CO 3 and photoexcited catalysts (PCET-a).…”

Combining Hydrodefluorination and Defluorophosphorylation for Chemo- and Stereoselective Synthesis of gem-Fluorophosphine Alkenes

“…Zhou and co-workers described a one-pot, two-step, three-component defluorinative annulation of trifluoromethyl alkenes, alkenes, and sodium sulfinates under photocatalysis . Very recently, the dual C–F bond functionalization of trifluoromethyl alkenes for accessing a monofluorocyclohexene framework was enabled through a stepwise photoredox radical/polar crossover procedure . Inspired by these elegant works and in continuation of our interest in defluorinative reactions, we herein presented a formal hydrophosphorylation reaction of β-CF 3 -substituted enones by combining hydrodefluorination and defluorophosphorylation in one pot.…”

“…On the basis of these control experiments and previous reports, we proposed a plausible reaction mechanism (Scheme ). − Initially, the carbonyl-containing trifluoromethyl alkenes react with reductive PhSiH 3 to realize hydrodefluorination through an S N 2′-type nucleophilic process and a simultaneous carbonyl reduction, leading to gem -difluorinated alkene B (pathway a). Subsequently, phosphoryl anion D selectively adds to the highly electrophilic α-position in gem -difluoroalkenes, followed by β-fluorine elimination to deliver the desired product 3 .…”

“…13 Very recently, the dual C−F bond functionalization of trifluoromethyl alkenes for accessing a monofluorocyclohexene framework was enabled through a stepwise photoredox radical/polar crossover procedure. 14 Inspired by these elegant works and in continuation of our interest in defluorinative reactions, 15 we herein presented a formal hydrophosphorylation reaction of β-CF 3 -substituted enones by combining hydrodefluorination and defluorophosphorylation in one pot. This three-component tactic has high versatility for the chemo-, regio-, and stereoselective synthesis of skeletally important (Z)-gem-fluorophosphine alkenes.…”

Photoredox Catalyzed [3 + 2]-Annulation Reaction of Pyridinium 1,4-Zwitterionic Thiolates with Alkenes: Synthesis of Dihydrothiophenes

“…In path B, radical intermediate III is reduced to zwitterion IV first. Then the product P2 is obtained via the elimination of pyridine . The results of density functional theory (DFT) calculations indicated that the free energy of zwitterion IV is 7.41 kcal/mol lower than that of diradical V (see the Supporting Information).…”