Decarboxylative halogenation, or halodecarboxylation, represents one of the fundamental key methods for the synthesis of ubiquitous organic halides. The method is based on conversion of carboxylic acids to the corresponding organic halides via selective cleavage of a carbon–carbon bond between the skeleton of the molecule and the carboxylic group and the liberation of carbon dioxide. In this review, we discuss and analyze major approaches for the conversion of alkanoic, alkenoic, acetylenic, and (hetero)aromatic acids to the corresponding alkyl, alkenyl, alkynyl, and (hetero)aryl halides. These methods include the preparation of families of valuable organic iodides, bromides, chlorides, and fluorides. The historic and modern methods for halodecarboxylation reactions are broadly discussed, including analysis of their advantages and drawbacks. We critically address the features, reaction selectivity, substrate scopes, and limitations of the approaches. In the available cases, mechanistic details of the reactions are presented, and the generality and uniqueness of the different mechanistic pathways are highlighted. The challenges, opportunities, and future directions in the field of decarboxylative halogenation are provided.

Spectral and acid-base properties of 7-hydroxyflavone (7HF) in the ground and excited states were investigated with a purpose to enable reasonable application of this dye and its derivatives as fluorescent probes. Analysis of solvatochromic and solvatofluorochromic ability of 7HF in 20 solvents, investigations of 7HF spectral properties in the frozen solvents, spectrophotometric and spectrofluorimetric titrations in methanol-water (4:1 v/v) in the wide pH/H0 range (from pH = 11.0 to H0 = -4.5), analysis of the 3D fluorescence and time-resolved spectra, as well as quantum-chemical calculations were carried out. It has been found that 7HF can exist in three protolythic forms-neutral, anion, and cation-depending on the environment acidity or basicity. In the excited state, in methanol-water solutions, there are four forms: neutral, cation and anion, which can be formed by direct excitation of the ground-state anion or by photodissociation of the neutral form depending on pH, and only one phototautomer, which appears in the H0 range from 1.3 to -4.5. It has been shown that the mechanism of the phototautomer formation depends on medium acidity. The photoautomer can be formed by cation photodissociation as well as by photoanion protonation. Finally, it was concluded which of the 7HF protolytic forms can be used for fluorescent probing.

Methods for synthesis of chiral organic compounds bearing trifluoromethyl-substituted stereocenters are of great interest for agrochemical and pharmaceutical labs and industries in their search for new bioactive materials. We report on employment of bisfunctionalized electrophiles, bearing both a trifluoromethyl and a functional group as direct substituents of the reactive center, in cross-coupling reactions. We exemplify this concept in the asymmetric synthesis of enantioenriched α-trifluoromethyl- and perfluoroalkyl-containing benzylic and allylic ethers and alcohols by nickel-catalyzed stereoconvergent Hiyama cross-coupling reaction. Substrate electrophiles are conveniently prepared in few steps from trifluoroacetic acid. The method represents a conceptually different approach to chiral CF3-substituted alcohols and ethers and allows for a rapid catalytic preparation of a wide range of these valuable compounds in high yields and enantioselectivity.

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The first example of direct C–H bond monofluoroalkylation with 1‐fluoro‐1‐haloalkanes with no adjacent functional groups and with β‐hydrogens has been developed. This transformation offers a straightforward route for the synthesis of a series of monofluoroalkylated benzoxazoles.

Herein we report the synthesis and application of a versatile class of N-heterocyclic carbene ligands based on an imidazo­[1,5-a]­pyridine-3-ylidine backbone that is fused to a chiral oxazoline auxiliary. The key step in the synthesis of these ligands involves the installation of the oxazoline functionality via a microwave-assisted condensation of a cyano-azolium salt with a wide variety of 2-amino alcohols. The resulting chiral bidentate NHC-oxazoline ligands form stable complexes with rhodium­(I) that are efficient catalysts for the enantioselective hydrosilylation of structurally diverse ketones. The corresponding secondary alcohols are isolated in good yields (typically >90%) with good to excellent enantioselectivities (80–93% ee). The reported hydrosilylation occurs at ambient temperatures (40 °C), with excellent functional group tolerability. Even ketones bearing heterocyclic substituents (e.g., pyridine or thiophene) or complex organic architectures are hydrosilylated efficiently, which is discussed further in this report.

We describe a highly efficient approach toward α-CF3-substituted benzhydryls thanks to the employment of organotitanium­(IV) based nucleophiles. The use of commercially available anesthetic halothane as a cheap fluorinated building block in a sequential one-pot nickel-catalyzed enantioselective cross-coupling reaction of aryl titanates allowed for the synthesis of chiral α-CF3-substituted benzhydryls in good yields and excellent enantioselectivities. Alternatively, α-CF3-benzyl bromides could be employed under similar conditions to obtain the same family of compounds in higher yields and excellent selectivities. A benzhydryl moiety is a common motif in many biologically active compounds, and their enantioenriched fluorinated analogs should be of great interest in the search for novel drugs and agrochemicals.

A chiral iridium carbene‐oxazoline catalyst is reported that is able to directly and efficiently hydrogenate a wide variety of ketones in excellent yields and good enantioselectivity (up to 93 % ee). Moreover, when using racemic α‐substituted ketones, excellent diastereoselectivities were obtained (dr 99:1) by dynamic kinetic resolution of the in situ formed enolate. Overall, the herein described hydrogenation occurs under ambient conditions using low hydrogen pressures, providing a direct and atom efficient method towards chiral secondary alcohols.