Direct Dehydroxytrifluoromethylthiolation of Alcohols Using Silver(I) Trifluoromethanethiolate and Tetra-n-butylammonium Iodide

Recent Advances in the Synthesis and Transformation of Carbamoyl Fluorides, Fluoroformates, and Their Analogues

Carbamoyl fluorides, fluoroformates, and their analogues are a class of important compounds and have been evidenced as versatile building blocks for the preparation of useful molecules in organic chemistry. While major achievements were made in the synthesis of carbamoyl fluorides, fluoroformates, and their analogues in the last half of 20th century, an increasing number of reports have focused on using O/S/Se=CF2 species or their equivalents as the fluorocarbonylation reagents for the direct construction of these compounds from the parent heteroatom-nucleophiles in recent years. This review mainly summarizes the advances in the synthesis and typical application of carbamoyl fluorides, fluoroformates, and their analogues by the halide exchanges and fluorocarbonylation reactions since 1980.

Nucleophilic and Radical Heptafluoroisopropoxylation with Redox-Active Reagents

The heptafluoroisopropyl group (CF(CF₃ )₂ ) is prevalent in pharmaceuticals and agrichemicals. However, heptafluoroisopropoxylated (OCF(CF₃ )₂ ) compounds remain largely underexplored, presumably due to the lack of efficient access to these compounds. Herein, we disclose the practical and efficient heptafluoroisopropoxylation reactions through the invention of a series of redox-active N-OCF(CF₃ )₂ reagents. These reagents were readily prepared from the oxidative heptafluoroisopropylation of hydroxylamines with AgCF(CF₃ )₂ . The substitutions on the nitrogen atom significantly affected the properties and reactivities of N-OCF(CF₃ )₂ reagents. Accordingly, two types of N-OCF(CF₃ )₂ reagents including N-OCF(CF₃ )₂ phthalimide A and N-OCF(CF₃ )₂ benzotriazolium salt O' were used as OCF(CF₃ )₂ anion and radical precursors, respectively. This protocol enables the direct heptafluoroisopropoxylation of a range of substrates, delivering the corresponding products in moderate to excellent yields.

Radical-Promoted Distal C-H Functionalization of C(sp3 ) Centers with Fluorinated Moieties

Due to their unique properties, fluorinated scaffolds are pivotal compounds in pharmaceuticals, agrochemicals, and materials science. Over the last years, the development of versatile strategies for the selective synthesis of fluorinated molecules by direct C-H bond functionalization has attracted a lot of attention. In particular, the design of novel transformations based on a radical process was a bottleneck for distal C-H functionalization reactions, offering synthetic solutions for the selective introduction of fluorinated groups. This Minireview highlights the major contributions in this blossoming field. The development of new methodologies for the remote functionalization of aliphatic derivatives with various fluorinated groups based on a 1,5-hydrogen atom transfer process and a β-fragmentation reaction will be showcased and discussed.

Redefining the Mechanistic Scenario of Carbon-Sulfur Nucleophilic Coupling via High-Valent Cp*CoIV Species

The potential access to Co^IV species for promoting transformations that are particularly challenging at Co^III still remains underexploited in the context of Cp*Co-catalyzed C-H functionalization reactions. Herein, we disclose a combined experimental and computational strategy for uncovering the participation of Cp*Co^IV species in a Cp*Co-mediated C-S bond-reductive elimination. These studies support the intermediacy of high-valent Cp*Co species in C-H functionalization reactions, under oxidative conditions, when involving nucleophilic coupling partners.

Efficient Synthesis of Trifluoromethyl Amines through a Formal Umpolung Strategy from the Bench-Stable Precursor (Me4 N)SCF3

Reported herein is the one‐pot synthesis of trifluoromethylated amines at room temperature using the bench‐stable (Me₄N)SCF₃ reagent and AgF. The method is rapid, operationally simple and highly selective. It proceeds via a formal umpolung reaction of the SCF₃ with the amine, giving quantitative formation of thiocarbamoyl fluoride intermediates within minutes that can readily be transformed to N‐CF₃. The mildness and high functional group tolerance render the method highly attractive for the late‐stage introduction of trifluoromethyl groups on amines, as demonstrated herein for a range of pharmaceutically relevant drug molecules.

Enantioselective Trifluoromethylthiolating Lactonization Catalyzed by an Indane-Based Chiral Sulfide

Enantioselective trifluoromethylthiolation, especially of alkenes, is a challenging task. In this work, we have developed an efficient approach for enantioselective trifluoromethylthiolating lactonization by designing an indane-based bifunctional chiral sulfide catalyst and a shelf-stable electrophilic SCF3 reagent. The desired products were formed with diastereoselectivities of >99:1 and good to excellent enantioselectivities. The transformation represents the first enantioselective trifluoromethylthiolation of alkenes and the first enantioselective trifluoromethylthiolation that is enabled by a catalyst with a Lewis basic sulfur center.

Visible-Light-Promoted Trifluoromethylthiolation of Styrenes by Dual Photoredox/Halide Catalysis

Herein, we report a new visible-light-promoted strategy to access radical trifluoromethylthiolation reactions by combining halide and photoredox catalysis. This approach allows for the synthesis of vinyl-SCF3 compounds of relevance in pharmaceutical chemistry directly from alkenes under mild conditions with irradiation from household light sources. Furthermore, alkyl-SCF3-containing cyclic ketone and oxindole derivatives can be accessed by radical-polar crossover semi-pinacol and cyclization processes. Inexpensive halide salts play a crucial role in activating the trifluoromethylthiolating reagent towards photoredox catalysis and aid the formation of the SCF3 radical.

Difluorocarbene-Derived Trifluoromethylthiolation and [(18)F]Trifluoromethylthiolation of Aliphatic Electrophiles

The first trifluoromethylthiolation and [(18)F]trifluoromethylthiolation of alkyl electrophiles with in situ generated difluorocarbene in the presence of elemental sulfur and external (radioactive) fluoride ion is described. This transition-metal-free approach is high yielding, compatible with a variety of functional groups, and operated under mild reaction conditions. The conceptual advantage of this exogenous-fluoride-mediated transformation enables unprecedented syntheses of [(18)F]CF3S-labeled molecules from most commonly used [(18)F]fluoride ions. The rapid radiochemical reaction time (≤1 min) and high functional-group tolerance allow access to a variety of aliphatic [(18)F]CF3S compounds in high yields.