K. Rubina

O-Alkylation of Pyridine Aldoximes Under Phase-Transfer Conditions

Abstract Phase-transfer catalysed alkylation of (E)-pyridine aldoximes with alkyl and benzyl halides in the benzene/10% aq. NaOH system in the presence of tetraoctylammonium bromide proceeds regiospecifically to afford the corresponding O-ethers in good yield.

Hydrosilylation of Pyridinealdehydes and Acetylpyridines Catalyzed by Caesium Fluoride in the Presence of 18-Crown-6

Abstract Reactions of isomeric pyridinealdehydes and acetylpyridines with dime thylphenylsi lane proceed readily in dichloromethane in the presence of catalytic amounts of CsF and 18-crown-6 to give silyl ethers of the corresponding pyridyl carbinols in good yields (50–70%).

Asymmetric reduction of aromatic and hetero cyclic ketones by hydrosilylation and hydrogen transfer in the presence of optically active rhodium catalysts

A study has been made of enantioselective hydrosilylation and reduction, by hydrogen transfer, of prochiral alkyl phenyl ketones or alkyl hetaryl ketones over various optically active catalysts. A total of 14 aromatic and heterocyclic carbinols were synthesized with preparative yields of 54–100%. The most effective catalytic systems were found to be complexes of RhCl3 and [Rh(cod)Cl]2 with the known optical inductor (S,S)-i-Pr-Pybox, with which we have obtained for the first time a series of heterocyclic secondary alcohols with an enantioselectivity of 20–63%.

Synthesis of Isopropyl and Tert-butyl Pyridyl Ketones by Alkylation of Acetylpyridines with Methyl Iodide Using Phase Transfer Catalysis

Abstract Isomeric acetylpyridines undergo regiospecific alkylation with methyl iodide under solid/liquid phase transfer conditions (aromatic solvent/KOH/18-crown-6) to give the corresponding isopropyl and/or tert-butyl pyridyl ketones, depending on reaction conditions.

Prototropic Rearrangement of 2-Propynyl(methyl)amino, 2-Propynyloxy, and 2-Propynylsulfanyl Derivatives of Hetarenes under Conditions of Phase-Transfer Catalysis: Mechanism and Limitations

Abstract2-Propynyl derivatives of N-methylaniline, phenol, benzenethiol, 2-pyridinethiol, 2-pyrimidinethiol, and 1,3-benzoxazole-2-thiol were synthesized. Under conditions of phase-transfer catalysis, phenyl 2-propynyl sulfide is converted into allenyl phenyl sulfide and phenyl 1-propynyl sulfide. The rearrangement mechanism was studied by the AM1 quantum-chemical method.

Synthesis, structure, and cytotoxicity of O-[3-(5-tetrazolyl)propyl]oximes

A two-stage method was developed for the conversion of phenyl-and pyridylaldoximes and ketoximes into the corresponding O-[3-(5-tetrazolyl)propyl]oximes. The structure of the sodium salt of 2-acetylpyridine O-[3-(5-tetrazolyl)propyl]oxime was established X-ray diffraction analysis. This compound was shown to possess a high cytotoxic activity in vitro.

Synthesis of pyridylphenyl ketoxime O-esters in conditions of phase-transfer catalysis

Alkylation of pyridylphenyl ketoximes with alkyl, allyl, and benzyl halides in conditions of phase-transfer catalysis yields the corresponding O-esters with a good yield. Partial Z,E -isomerization takes place during the reaction.

FREE RADICAL CHLORINATION OF METHYL DERIVATIVES OF PYRIDINE, PYRAZINE, AND THIAZOLE BY N-CHLOROSUCCINIMIDE

When methylazines (2-, 3-, and 4-methylpyridines, methylpyrazine) are treated with N-chlorosuccinimide they undergo successive chlorination of the methyl group to give 2-chloromethylpyridine, 2-dichloromethylpyridine, and dichloromethylpyrazine in preparative yields. 3-Dichloromethylpyridine was synthesized from pyridine-3-aldehyde and PC15. The primary chlorination products of 4-methylthiazole are 4-methyl-5-chlorothiazole and 5-chloro-4-chloromethylthiazole.

Synthesis of 5-arylpyrimidine-2-carboxylic acids and the liquid-crystal characteristics of their aryl esters

Abstract5-Arylpyrimidine-2-carboxylic acids were synthesized by the hydrolysis of 5-aryl-2-cyanopyrimidines and the oxidation of 5-aryl-2-styrylpyrimidines under the conditions of phase-transfer catalysis. The aryl esters of the acids were obtained, and their liquid-crystal characteristics were studied. The p-substituted aryl esters of 5-phenylpyrimidine-2-carboxylic acid do not exhibit mesomorphism, but the introduction of a butyloxy group at the p position of the phenyl residue leads to the appearance of nematic characteristics. Aryl 5-phenylpyrimidinylcarbonyloxy-benzoates are nematic liquid crystals with a thermally stable meso phase and an existence range of 50–80 °C.

Halogenation of propargyl ethers of heterylaldoximes and ketoximes under interphase catalysis conditions

The halogenation of propargyl ethers of heterylaldoximes and ketoximes in interphase catalytic systems CX4 (X=Cl, Br)/solid KOH/18-crown-6 leads selectively to the formation of the corresponding O-(halopropargyl)oximes.