This review discusses recent advances in the chemistry of saturated boronic acids, boronates, and trifluoroborates. Applications of the title compounds in the design of boron-containing drugs are surveyed, with special emphasis on α-amino boronic derivatives. A general overview of saturated boronic compounds as modern tools to construct C(sp 3 )À C and C(sp 3 )-heteroatom bonds is given, including recent developments in the Suzuki-Miyaura and Chan-Lam cross-couplings, single-electron-transfer processes including metallo-and organocatalytic photoredox reactions, and transformations of boron "ate" complexes. Finally, an attempt to summarize the current state of the art in the synthesis of saturated boronic acids, boronates, and trifluoroborates is made, with a brief mention of the "classical" methods (transmetallation of organolithium/magnesium reagents with boron species, anti-Markovnikov hydroboration of alkenes, and the modification of alkenyl boron compounds) and a special focus on recent methodologies (boronation of alkyl (pseudo)halides, derivatives of carboxylic acids, alcohols, and primary amines, boronative CÀ H activation, novel approaches to alkene hydroboration, and 1,2-metallate-type rearrangements).

A facile synthetic route toward either 3- or 5-fluoroalkyl-substituted isoxazoles or pyrazoles containing an additional functionalization site was developed and applied on a multigram scale. The elaborated approach extends the scope of fluoroalkyl substituents for introduction into the heterocyclic moiety, and uses convenient transformations of the side chain for incorporation of fluoroalkyl-substituted azoles into the structures of biologically active molecules. The utility of the obtained building blocks for isosteric replacement of alkyl-substituted isoxazole and pyrazole was shown by the synthesis of fluorinated Isocarboxazid and Mepiprazole analogues.

ABSTRACT:A technique of hydrophobic surface design with a high degree of structural homogeneity has been developed for catalytic materials. Mesoporous activated carbons and silica gel were modified by (A) treatment with vinyltrimethoxysilane (vtms) or (B) chlorination with carbon tetrachloride followed by reaction with a Grignard reagent. Evidence for silica gel modification was obtained from FT-IR and 13 C NMR spectroscopy and from elemental analysis. Carbons chemically modified with alkanes and olefins were studied using thermogravimetry (TG) and the results compared with those for the modified silica gel. TG and differential scanning calorimetry (DSC) revealed that the polymerisation of vinyl groups occurred on the carbon surface. The participation of the carrier surface in the initiation of radical processes has been discussed.

An efficient approach towards introducing (cyclo)alkyl substituents at C‐2, C‐3 or C‐4 positions of the piperidine ring was described. The method relied on the straightforward two‐step reaction sequence based on the formal sp3–sp3 retrosynthetic disconnection. The procedure commenced with selective directed ortho metalation of 2‐ and 3‐bromopyridine, followed by reaction with aldehydes or ketones. The optimized methods were developed for all three isomers of hydroxyalkyl‐substituted pyridines, which were synthesized in 28–84 % overall yield (20 examples). Catalytic hydrogenation of these adducts could be performed selectively with or without retention of the hydroxyl group in their molecules, so that either (cyclo)alkylpiperidines (14 examples) or the corresponding saturated amino alcohols (16 examples) were obtained (28–96 % and 82–96 % yield, respectively). After minor modifications, the developed method was also implemented in a flow reactor and a 5 L autoclave, which allowed for the preparation of up to 0.5 kg of the representative (cyclo)alkylpiperidines.

The synthetic utility of 2‐trifluoromethyl‐1H‐pyrrole as a pharmaceutically relevant platform was demonstrated by the preparation of mono‐ and bifunctional C‐2(5)‐ or C‐3‐substituted derivatives, i.e. regioisomeric sulfonyl halides, carboxylic acids, aldehydes, and nitriles. A series of modifications relied on lithiation or electrophilic substitution, which proceeded regioselectively on multigram scale, mostly in protecting‐group‐free mode. Subsequent catalytic hydrogenation of the pyrrole ring was also performed for synthesis of all isomeric 2‐trifluoromethyl α‐ and β‐prolines. These derivatives were considered as promising low‐molecular‐weight building blocks for synthesis, drug discovery, and agrochemistry.

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In this research, the oxidation of a series of benzoins, R-C(=O)-CH(OH)-R, where R = phenyl, 4-methoxyphenyl, 4-bromophenyl, and 2-naphthyl, by hydrogen peroxide in the presence of nanostructured HKUST-1 (suspension in acetonitrile/water mixture) was studied. The respective benzoic acids were the only products of the reactions. The initial average reaction rates were experimentally determined at different concentrations of benzoin, H2O2 and an effective concentration of HKUST-1. The sorption of the isotherms of benzoin, dimethoxybenzoin and benzoic acid on HKUST-1, as well as their sorption kinetic curves, were measured. The increase in H2O2 concentration expectedly led to an acceleration of the reaction. The dependencies of the benzoin oxidation rates on the concentrations of both benzoin and HKUST-1 passed through the maxima. This finding could be explained by a counterplay between the increasing reaction rate and increasing benzoin sorption on the catalyst with the increase in the concentration. The electronic effect of the substituent in benzoin had a significant influence on the reaction rate, while no relation between the size of the substrate molecule and the rate of its oxidation was found. It was confirmed by DFT modeling that the reaction could pass through the Baeyer–Villiger mechanism, involving an attack by the HOO– anion on the C atom of the activated C=O group.