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The oxidation of N acetyl and N benzoylanabasine with the tert butyl hydroperoxide (TBHP)-МoCl 5 system or МCРBA proceeds selectively at the nitrogen atom of the pyridine ring. The oxidation of N methylanabasine under similar conditions gives a mixture of stereo isomeric N oxides at the piperidine nitrogen atom, their ratio depending on the reagent used. The oxidation of anabasine by TBHP-МoCl 5 or МCРBA is accompanied by dehydrogenation and results in anabaseine N oxide. The reactions of anabasine and anabaseine pyridine N oxides with acetic anhydride were investigated. The substituted 1H 3 pyridin 2 ones were prepared. 2 pyridone, N acetylpiperidyl 2 pyridone, anabasein 3 one.Anabasine, 3 (2 piperidyl)pyridine (1), is the princi pal alkaloid of the Anabasis aphylla L. plant. 1 Anabasine hydrochloride is used as a means for giving up smoking; 2 the mechanism of its action includes binding to nicotine sensitive receptors. The anabasine base exhibits clear cut physiological activity. The action of this alkaloid is due to affection of the H cholinoreactive structures of various parts of the nervous system and violation of the mem brane permeability of cells, which results in a faulty course of redox processes in the organism. 3 Anabasine is an initial base in the synthesis of revers ible and irreversible choline esterase inhibitors, 4 in par ticular, phosphamide, 5 carbamide derivatives, 6 and a number of pharmacologically valuable compounds ob tained by reactions at the piperidine ring nitrogen atom. 7,8 Anabasine derivatives containing bulky acyl and alkyl sub stituents at the piperidine ring nitrogen atom exert an antinicotinic action, 9 and its hydrogenated derivatives ex hibit analgesic activities. 10 Thus, targeted synthetic transformations of anabasine may produce effective analogues with other types of physi ological activities.This paper describes a study of the oxidation of ana basine (1) and its N acetyl (2), N benzoyl (3) and N methyl (4) derivatives on treatment with tert butyl hydroperoxide (TBHP) and МCРBA and some transfor mations of the N oxides thus formed. Results and DiscussionPreviously, 11 we demonstrated that anabasine oxida tion with hydrogen peroxide in acetic acid is accompa nied by cleavage of the piperidine ring. No N oxidation of anabasine or its derivatives 2-4 by other reagents has yet been carried out. We found that refluxing of anabasine (1) in the presence of the TBHP-MoCl 5 system in benzene with water removal gives crystalline anabaseine N oxide (5) in 54% yield (Scheme 1). Thus, the hydroperoxide serves as a dehydrogenating agent. The oxidation of N acetyl (2) or N benzoylanabasine (3) under the ac tion of TBHP-MoCl 5 affords individual N acetyl and N benzoylanabasine pyridine N oxides 6 and 7 in 79 and 89% yields, respectively. It should be emphasized that previously, this reagent has been successfully used for N oxidation of diverse pyridine derivatives. 12-14 The use of VO(acac) 2 as the catalyst proved inefficient. The at tempted N oxidation of anabasine derivatives 2 and ...

Compounds of the pyrazine series, including pyrazinecarboxylic acid amides, are widely used in the production of various drugs. One of the well known compounds in this seties is 2-pyrazinecarboxylic acid amide, known as the antituberculous drug pyrazinamide. We have established that this drug can be synthesized with a high yield by oxidative ammonolysis of 2-methylpyrazine [1]. It was found that the process, proceeding in an aqueous ammonia solution, involves oxidation of the methyl group to nitrile, followed by its conversion into amide in the course of high-temperature hydrolysis. By the same token, during oxidative ammonolysis of 2,5-dimethylpyrazine (I) on a molybdenum-cerium -titanium mixed oxide catalyst, the initial compound converted sequentially into 5-methylpyrazine-2-carboxamide (II) and 2,5-pyrazinedicarboxamide (III) [2].Below we present the results of investigation of the oxidative ammonolysis of compound I in the presence of three samples of catalysts representing a molybdenum-antimony -titanium mixed oxide system. The samples had the same molar ratio MoO3/Sb203 = 1 : 0.5 and a variable relative content of TiO2: 0.25, 0.50, and 0.75 mole TiO2 per mole MoOs.Selection of this catalyst system was based on the known facts evidencing that the presence of antimony oxides markedly facilitates the oxidative ammonolysis of organic compounds [3,4]. Antimony oxides favor the activation of oxygen supplied from the gas phase to the contact zone [5] and, under certain conditions, may generate or regenerate active centers on the surface of MOO3, acting by a mechanism of the "remote control" type [6].The results obtained in our experiments indicate that the oxidative ammonolysis of compound I involves both the for- mation of partial oxidation products and products of more profound transformations. The oxidative ammonolysis of 2,5-dimethylpyrazine (I) with the formation of amides II and III is accompanied by the demethylation of compound I with the formation of 2-methylpyrazine (IV) and pyrazine (VI). Compound IV converts into the target 2-pyrazinecarboxylic acid amide (V). Also observed, albeit in trace amounts, was 2,5-pyrazine polyamide (VII). All the above substances were isolated from the reaction mixture and identified. 381 VIQualitative composition of the products of oxidative ammonolysis of compound I was the same for all the three catalysts. However, the quantitative ratio of the products was markedly different, depending on the content of titanium dioxide in the sample and on the temperature (Table 1).The first catalyst sample had the oxide component ratio degree of conversion increased from 25 to 100% when the process temperature rose from 320 to 420~ The main reaction product was pyrazinamide (V), the yield of which also increased in the temperature range studied to reach 76% at 420~ Analysis of the reaction mixture revealed, besides amide V, the presence of pyrazines II, III, IV, and VI. The maximum yield of diamide III did not exceed 5-6%, being virtually independent of the temperature. Approximately...

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