Difluorophenylsulfanylmethyl Radical and Difluoromethylene Diradical Synthons: gem-Difluoromethylene Building Block

Cathodic generation of reactive (phenylthio)difluoromethyl species and its reactions: mechanistic aspects and synthetic applications

The cathodic reduction of bromodifluoromethyl phenyl sulfide (1) using o-phthalonitrile as a mediator generated the (phenylthio)difluoromethyl radical, which reacted with α-methylstyrene and 1,1-diphenylethylene to provide the corresponding adducts in moderate and high yields, respectively. In contrast, chemical reduction of 1 with SmI₂ resulted in much lower product yields. The detailed reaction mechanism was clarified based on the cathodic reduction of 1 in the presence of deuterated acetonitrile, CD₃CN.

Multigram Synthesis of Advanced 6,6-Difluorospiro[3.3]heptane-derived Building Blocks

A convenient methodology for constructing 6,6-difluorospiro[3.3]heptane scaffold - a conformationally restricted isostere of gem-difluorocycloalkanes - is developed. Alarge array of novel 2-mono- and 2,2-bifunctionalized difluorospiro[3.3]heptane building blocks was obtained through the convergent synthesis strategy using a common synthetic precursor - 1,1-bis(bromomethyl)-3,3-difluorocyclobutane. The target compounds and intermediates were prepared by short reaction sequences (6-10 steps) on multigram scale (up to 0.47 kg).

Transition-Metal-Free Decarboxylative Cyclization of N-Arylacrylamides with 2,2-Difluoro-2-(phenylthio)acetic Acid: Synthesis of Thiodifluorooxindole Derivatives

An efficient transition-metal-free decarboxylative cyclization of N-arylacrylamides with 2,2-difluoro-2-(phenylthio)acetic acid for the construction of thiodifluoroindoleone derivatives is described. This strategy features stable and readily available substrates, mild reaction conditions, and transition-metal-free catalysts. Notably, this protocol has successfully applied to synthesis of gem-difluoroalkenes, which exist in numerous biologically active compounds.

Visible light-mediated atom transfer radical addition to styrene: base controlled selective (phenylsulfonyl)difluoromethylation

A visible-light-mediated (phenylsulfonyl)difluoromethylation of styrenes has been developed to afford both ATRA and heck-type products by simply tuning the bases.

Fluoroalkylation of Various Nucleophiles with Fluoroalkyl Sulfones through a Single Electron Transfer Process

The fluoroalkylation of various nucleophilic reagents with (phenylsulfonyl)difluoromethyl (PhSO₂CF₂)-substituted phenanthridines was achieved to give fluorinated phenanthridine derivatives, which enables the construction of both carbon-heteroatom and carbon-carbon bonds via the substitution of the phenylsulfonyl group. Mechanistic studies indicated that these reactions proceed through a unimolecular radical nucleophilic substitution (S_RN1) mechanism. It is worthwhile noting that in the cases of O-nucleophiles ( t-BuO^- and PhO^-), the addition of t-BuOK/PhCHO could significantly promote the reactions, due to the in situ formation of a highly reactive electron donor species through the interaction of t-BuOK, PhCHO, and the solvent DMF, which can effectively initiate the single electron transfer process.

Visible-light-mediated radical arylthiodifluoromethylation of isocyanides with fluorinated 2-pyridyl sulfones

2-PySO₂CF₂SAr were developed as powerful arylthiodifluoromethylation reagents, and the Stern–Volmer luminescence studies demonstrated that the mechanism might operate via a photoredox cycle consisting of a reductive quenching with Na₂CO₃.

Tandem radical cyclization for the construction of 1-difluoroalkylated isoquinolines via Cu catalyzed and visible light-promoted pathways

A Cu/B₂pin₂ system promoted cyclization for the synthesis of 1-difluoroalkylated isoquinolines with vinyl isocyanides and bromodifluoroacetic derivatives in moderate to good yields was reported.

Synthesis of Tricyclic Spiranoid Lactones via I2/Sm(II)- and I2/Pd(0)-Mediated Cyclizations of a Common Cycloalkylmethylene Precursor

A general synthesis of phylogenetically and structurally different tricyclic angularly fused spiranoid lactones, frequently observed as scaffold segments of various biochemical compounds and drugs of natural origin, is demonstrated via controlled cyclization of simple and easily accessible cycloalkylmethylene key precursors. The rapid composition of the key architecture yields an assembly of stable bicyclic iodolactones, which are converted to form a wide range of angularly fused tricyclic scaffolds.

Visible light promoted carbodifluoroalkylation of allylic alcohols via concomitant 1,2-aryl migration

A novel visible light promoted carbodifluoroalkylation of allylic alcohols is disclosed.

A three-component synthesis of aryl(heteroaryl)acylamides

α-Heteroarylamides of diverse structures are assembled in a three-component reaction of azole or azineN-oxides, 1,1-difluorostyrenes and amines.

Introduction of fluorine and fluorine-containing functional groups

Over the past decade, the most significant, conceptual advances in the field of fluorination were enabled most prominently by organo- and transition-metal catalysis. The most challenging transformation remains the formation of the parent C-F bond, primarily as a consequence of the high hydration energy of fluoride, strong metal-fluorine bonds, and highly polarized bonds to fluorine. Most fluorination reactions still lack generality, predictability, and cost-efficiency. Despite all current limitations, modern fluorination methods have made fluorinated molecules more readily available than ever before and have begun to have an impact on research areas that do not require large amounts of material, such as drug discovery and positron emission tomography. This Review gives a brief summary of conventional fluorination reactions, including those reactions that introduce fluorinated functional groups, and focuses on modern developments in the field.

Selective fluoroalkylations with fluorinated sulfones, sulfoxides, and sulfides

Efficient fluoroalkylations have been proven to be a highly useful strategy for the synthesis of bioactive fluorine-containing compounds and other materials. The design and use of a single category of reagents for multiple synthetic goals are much more attractive to preparative organic chemists. In this Account, we show how we have succeeded in the nucleophilic trifluoromethylation, difluoromethylation, difluoromethylenation, (phenylsulfonyl)difluoromethylation, (phenylthio)difluoromethylation, and monofluoromethylation as well as radical (phenylsulfonyl)difluoromethylation and electrophilic difluoromethylation by using fluorinated sulfones, sulfoxides, sulfides, or fluorinated sulfonium salts. The chemistry not only provides practically powerful synthetic methods, but the molecular design concept that we have developed may also be adopted to tackle other related chemical problems.