Reactions of nucleophilic substitution of 4-aryl-5-carbomethoxy-6-methyl-2-chloro-3-cyanopyridines

Methods of synthesis of 5-carbomethoxy-substituted pyrazolo[3,4-b]pyridines and 3H-imidazo[4,5-b]pyridines by their reaction with hydrazine hydrate or as a result of Hofmann rearrangement of the corresponding 2-aminopyridines were developed based on 4-aryl-3-carbamoyl(or cyano)-5-carbomethoxy-6-methyl-2-chloropyridines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No.12, pp. 1646–1650, December 1992.     

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

2-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.     

13C NMR Spectra of 8-mercaptoquinoline derivatives

The additivity of the effect of the increments of the substituents on the ¹³C chemical shifts in polysubstituted quinolines is demonstrated. In the case of substitution in the pyridine part of quinoline (R = CH₃, OCH₃, SCH₃) the ortho increments are depressed as compared with the increments in benzene derivatives. This is associated with a change in the charge on the ring carbon atom and polarization of the C-H bond because of steric hindrance.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 937–940, July, 1981.     

A simple one pot synthesis of 1-(s-triazolo[4,3-x]azinyl-3)-substituted polyols

Open-chain C-nucleosides, 1-(s-triazolo[4,3-x]azinyl-3)polyols 13–18 were prepared by one-pot synthesis from hydrazinoazines 20a,c and various D-aldoses 1–6. No protective groups were required for these transformations. 1-(s-Triazolo[4,3-b]pyridazinyl-3)-D-xylo-tetritol (15a) was isolated and characterised in the form of its 4-O-triphenylmethyl derivative 19. Reaction of hydrazinopyridazines 20a,b with methyl 2,3-di-O-acetyl-L-threuronate ( 22 ), followed by treatment with bromine, gave the corresponding (2R,3S)-2,3-diacetoxy-3-(s-triazolo[4,3-b]pyridazinyl-3)propanoic acid methyl esters 24a,b. Acetonisation of 1-(6-chloro-s-triazolo[4,3-b]pyridazinyl-3)-D-gluco-pentitol ( 17a ) gave a mixture of isomeric bis-acetonides 25 and 26 , while acetonisation of 1-(6-chloro-s-triazolo[4,3-b]pyridazinyl-3)-D-manno-pentitol ( 18a ) gave acetonide 27 as a single isomer.     

Comments on the stability criterion of Lienard and Chipart

Some comments are made on the stability criterion of Lienard and Chipart for the zeros of a polynomial to have negative real parts.     

Nitrosation and bromination of 6-(2'-furyl)imidazo[2,1-b]thiazole and its derivatives

The action of nitrosating agents and bromine on 6-(2-furyl)imidazo[2,1-b]thiazole and its 3-methyl, 5-bromo, and 5-nitro derivatives was studied. The structures of the products were proved by UV, IR, and PMR spectroscopy and thin-layer chromatography.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1353–1358, October, 1972.     

Alkylation of Aryl and Hetaryl Ketoximes with Alkyl Iodides Prepared In Situ from Alkyl Chlorides Under Phase Transfer Catalysis Conditions

Two simple one-pot phase transfer catalytic methods for the preparation of ketoxime O-ethers from the corresponding ketoximes and alkyl iodides prepared in situ from alkyl chlorides were developed. The corresponding aryl and hetaryl ketoxime O-ethers were obtained in 15–83% yields.     

Synthesis,structure and cytotoxic activity of 2‐acetyl‐5‐trimethylsilylthiophene(furan) and their oximes

5‐Trimethylsilylderivatives of 2‐acetylthiophene and ‐furan have been regioselectively prepared by a one‐pot procedure from the corresponding 2‐acetylfuran or 2‐acetylthiophene using lithium N‐methylpiperazide (LNMP)–butyllithium–trimethylchlorosilane–water as the sequence of reagents. The ketones obtained were converted to the corresponding oximes. The structure of 2‐acetyl‐5‐trimethylsilylthiophene oxime (E‐isomer) has been studied by X‐ray diffraction. Formation of centrosymmetric dimers by means of H‐bonds has been observed. The intermolecular hydrogen bond O9? H…N8 length is 2.842(5) Å [H…N8 = 1.87 (6) Å, O9? H…N8 = 157(4)°]. Copyright © 2006 John Wiley & Sons, Ltd.     

Synthesis of derivatives of oxazolidin-5-ones

A method has been developed for the synthesis of derivatives of oxazolidin-5-one by the reaction of the corresponding N-benzyloxycarbonylaminoacid with formaldehyde in the presence of formic acid. Yields of derivatives of 3-benzyloxycarbonyloxazolidin-5-one increase with increased molecular weight of the initial compound. For the synthesis of 3-benzyloxycarbonyl-4-benzyloxazolidin-5-one the proposed method gives a higher yield than previously known methods. The reaction mechanism is discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 115–117, January, 1993.