Rapid incorporation of a difluoroacetate radical into para-quinone methides via radical 1,6-conjugate addition

Base-promoted triple cleavage of CCl2Br: a direct one-pot synthesis of unsymmetrical oxalamide derivatives

We present a novel, eco-friendly and one-pot approach for synthesizing unsymmetrical oxalamides with the aid of dichloroacetamide and amine/amides in the presence of CBr4 in a basic medium. The use of water as a potent supplement for the oxygen atom source and the detailed mechanism have been disclosed. Moreover, the protocol involves triple cleavage of CCl2Br and the formation of new C-O/C-N bonds, with the advantage of achieving selective bromination using CBr4 with good to excellent yield under mild conditions. The method also demonstrates promise for industrial use, as proven by its effective implementation in gram-scale synthesis conducted in a batch process, along with its utilization in a continuous-flow system.

Et2Zn-Mediated Radical (3 + 2) Cycloaddition of Vinyl Azides with Ethyl Iododifluoroacetate to Access 3,3-Difluoro-γ-lactams

A diethylzinc-mediated radical (3 + 2) cycloaddition of vinyl azides with ethyl iododifluoroacetate is presented. The developed reaction features good functional group tolerance, broad substrate scope, and operational simplicity, enabling efficient assembly of a wide range of 3,3-difluoro-γ-lactam derivatives bearing an O-substituted quaternary carbon center in moderate to good yields. The utility of the method is showcased by a scaled-up reaction, conversion of the product, and late-stage structural modifications of a variety of pharmaceutical compounds.

DMSO-promoted direct δ-selective arylation of p-quinone methenylpiperidine bearinides to generate fuchsones under metal-free conditions by employing p-QMs themselves or substituted phenols as aryl sources

Fuchsones have wide applications in modern society. Present methods for generating fuchsones have many disadvantages and there are significant limitations for further exploration of fuchsone applications. Herein, we describe a DMSO-promoted direct δ-selective arylation of p-QMs to synthesize symmetrical and unsymmetrical fuchsones under metal-free conditions by employing p-QMs themselves or substituted phenols as aryl sources. As unprecedented methods, these novel strategies present a great advantage and significance for further exploration of fuchsones and the development of new applications.

Synthesis of Selectively gem-Difluorinated Molecules; Chiral gem-Difluorocyclopropanes via Chemo-Enzymatic Reaction and gem-Difluorinated Compounds via Radical Reaction

The incorporation of fluorine atoms into an organic compound can alter the chemical reactivity or biological activity of the resulting compound due to the strong electron withdrawing nature of the fluorine atom. We have synthesized many original gem-difluorinated compounds and described the results in four sections. The first section describes the synthesis of optically active-gem-difluorocyclopropanes via the chemo-enzymatic reaction; we applied these compounds to liquid crystalline molecules, then further discovered a potent DNA cleavage activity for the gem-difluorocyclopropane derivatives. The second section describes the synthesis of selectively gem-difluorinated compounds via a radical reaction; we synthesized fluorinated analogues of a sex pheromone of the male African sugarcane borer, Eldana saccharina, and used the compounds as proof for investigating the origin of pheromone molecule recognition on the receptor protein. The third involves the synthesis of 2,2-difluorinated-esters by visible light-driven radical addition of 2,2-difluoroacetate with alkenes or alkynes in the presence of an organic pigment. The last section describes the synthesis of gem-difluorinated compounds via the ring-opening of gem-difluorocyclopropanes. We further developed a novel method of synthesizing gem-difluorohomoallylic alcohols via the ring-opening of gem-difluorocyclopropane and aerobic oxidation by photo-irradiation in the presence of an organic pigment. Since gem-difluorinated compounds that were prepared by the present method have two olefinic moieties with a different reactivity at the terminal position, we accomplished the synthesis of four types of gem-difluorinated cyclic alkenols via the ring-closing-metathesis (RCM) reaction.

Organophotoredox 1,6-Addition of 3,4-Dihydroquinoxalin-2-ones to para-Quinone Methides Using Visible Light

An organophotoredox 1,6-radical addition of 3,4-dihidroquinoxalin-2-ones to para-quinone methides catalyzed by Fukuzumi's photocatalyst is described under the irradiation of a HP Single LED (455 nm). The corresponding 1,1-diaryl compounds bearing a dihydroquinoxalin-2-one moiety (20 examples) are obtained with good to excellent yields under mild reaction conditions. Several experiments have been carried out in order to propose a reaction mechanism.

Cu-Catalyzed Three-Component Cascade Synthesis of 1,3-Benzothiazines from ortho-Aminohydrazones and Bromodifluoroacetamides

An efficient and convenient synthesis of benzo[d][1,3]thiazine has been developed by employing a copper-catalyzed transformation of readily available ketone-derived hydrazones with elemental sulfur and bromodifluoroalkylative reagents. The strategy involves an S₈-catalyzed selective triple-cleavage of bromodifluoroacetamides, which acts as a C1 synthon at the 2-position of benzo[d][1,3]thiazine. A mechanism proceeding through a Cu-carbene intermediate is proposed for the C-S bond formation.

Photoredox Polyfluoroarylation of Alkyl Halides via Halogen Atom Transfer

Polyfluoroarene moieties are of interest in medicinal chemistry, agrochemicals, and material sciences. Herein, we present the first polyfluoroarylation of unactivated alkyl halides via a halogen atom transfer process. This method converts primary, secondary, and tertiary alkyl halides into the respective polyfluoroaryl compounds in good yields in the presence of amide, carbamate, ester, aromatic, and sulfonamide moieties, including derivatives of complex bioactive molecules. Mechanistic work revealed that this transformation proceeds through an alkyl radical generated after the halogen atom transfer.

Photoinduced decarboxylative 1,6-addition of para-quinone methides with α-keto acids: an eco-friendly approach to α,α′-diarylated ketones

The photoinduced decarboxylative 1,6-addition of para-quinone methides with α-keto acids in an eco-friendly approach to α,α′-diarylated ketones is developed.

Copper-catalyzed 1,6-conjugate addition of para-quinone methides with diborylmethane

Presented herein is the first 1,6-conjugate addition of diborylmethane. This reaction features high yields, mild reaction conditions, and broad functional group compatibilities.