Oxidation of anabasine with hydrogen peroxide

O X I D A T I O N OF A N A B A S I N E W I T H H Y D R O G E N P E R O X I D E

Y a . L. G o l ' d f a r b , F. D. A l a s h e v , a n d V. K. Z v o r y k i n a

N. D. Zelinskii Institute of Organic Chemistry, Academy of Sciences, USSR Translated from Izvestiya Akademii Nauk SSSP,, No. 12, pp. 2209-2216, December, 1962 Original article submitted April 13, 1962

In a previous paper [1] we pointed out that in the oxidation of anabasine with hydrogen peroxide in acetic acid the piperidine ring of the molecule of this alkaloid is opened. We showed that the predominating product of this reaction is an optically inactive compound of composition CIoHI2NzO4, m.p. 229-231". In the present paper we report

�9 experimental data that enable us to assign the structure of 5 -(hydroxyimino)-3-pyridinevaleric acid 1-oxide (I) to this compound.

/ \

S0%H,O / " , , / I I - - ~ I II NOH

CH,COOH (I)

N Y 0

On the basis of purely formal considerations we may suggest several structures corresponding to the composition C10HI2N204, e.g. (I), (II), (III), and (IV), to the product of the oxidation of anabasine with hydrogen peroxide.

OH /

COCH~CH~CH2C

N

0 (II)

CON HCH~CH2CH~COOH CHCHzCOOH / I

"%/ \ / N N

0 0 (III) IV

In our experiments the oxidant was a mixture of 30% hydrogen peroxide and glacial acetic acid, i.e., a system in which peroxyacetic acid is also present [2]. The action of oxidizing agents of this type on amines often leads to the c leavage of an N - C bond ~I3] and references therein). It may therefore be supposed that the most probable structures for the compound isolated are fl) and (II), and not (III) and (IV), since the latter are formed as the result of the cleavage of a C - C bond; moreover, in the case of (IV) acylation of the amino group with acetic acid must be assumed. The fact that the action of hydrogen peroxide on primary and secondary amines leadsto the format ionofthc hydtoxy- imino group [3] formed grounds for supposing thatside reactions may occur also in the case of anabasine. If cleavage of the piperidine ring occurred at the N - C 0 ) bond, we could expect the formation of the hydroxamic acid flI), and if it occurred at the N - C ( e ) bond, then we could expect the hydroxyimino acid (I). Also, the character of the oxidizing agent made it very probable that the oxidation product would contain an N-oxide grouping on the pyridine ring [4].

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Study of the product of m.p. 229-231" formed from anabasine in 70% yield showed that it had the structure G)*. This view was based on its reactions and also on comparison with the synthetic product. Thus, when heated with hydrochloric acid, (I) formed a keto acid, which corresponded in composition and properties to 5-oxo-3-pyr id ine-

H O H ( I ) m _ ~

H �9

valeric acid 1-oxide (V).

COCH~CH~CH2CO0 H

0 (V) (VI)

~ \ o

In addition, the presence of a hydroxyimino group in the molecule of the compound under examination was shown by comparing its infrared absorption spectrum with the infrared spectra of several oximes** (Table 1).

TABLE 1

Compound

6 - (Hydroxyimino)- 3 - pyridinevaleric acid 1-oxide (I)

Acetophenone oxime 2-Hexanone oxime

C ~- N frequency (cm -I)

1637 1643 1670

As will be seen from Table 1, the C---- N frequency of the molecule (I) is extremely close to the C ~--~N frequency of acetophenone oxime and differs from the value for 2-hexanone oxime. This is in accord with the fact that in the first two cases we have conjugated systems.

As a compound having an acid function the oxidation product isolated formed an ester with ethanol (m.p. 144- 144.5~ By the act ion of zinc in acetic acid with heating, from the compound of m.p. 229-231 ~ we obtained a compound of composition CIoH1BN,O, corresponding to the lac-

tam of structure (VI). A lactam of such a structure, m.p. 1470, was obtained by Orekhov and co-workers [5a] by the oxidation of N-benzoylanabasine with potassium permanganate, hydrolysis of the benzoyl group, and cyelization. Our compound (VI) had m.p. 137-138" and differed in this respect from the lactam described. In this connection we must point out that only a racemic compound can be formed from a hydroxyimino acid of structure (I). The above authors state that in the formation of 6-benzamide-3-pyr id inevaler ic acid "complete racemizat ion occurs" [5b], so that the l ac tam that they obtained also could not rotate the plane of polarization. However, on repeating the experiments of Orekhov and co-workers on the preparation of the laetam of 6-amino-3-pyr id inevaler ic acid from N-benzoylana - basine, we found that it was optical ly active. It is probable, therefore, that the discrepancy in melt ing point between

TABLE 2

Compound

Lactam (VI) from 6-(hydroxyimino)-3- pyridinevaleric acid 1-oxide (I)

Lactam (VI) from N-benzoylanabasine

k max

26_._s 262

26_._~2 262

s max

3090 5275

3800 5265

Solvent

Alcohol alcoholic HCI(0.05N)

Alcohol alcohoHc HCI(0.05N)

our and their lactams arose from the fact that the above investigators were dealing with an optically active compound. Spectroscopic investigation of the two products showed that they had similar ultraviolet absorption spectra | (Table 2).

* When the substance of m.p. 229-231" had been separated from the products of the oxidation of anabasine there remained a syrupy mixture which gave qualitative reactions characteristic for hydroxamic acids. It is therefore quite probable that compounds of this type, e.g. (II), were formed in the oxidation. ** The spectra were determined in the Optical Laboratory of the Institute of Organic Chemistry of the Academy of Sciences by V. Morozov. ***The spectra were determined in the Optical Laboratory of the Institute of Organic Chemistry of the Academy of Sciences by L. A. Gorsheneva.

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That our compound, m.p. 137-138", was indeed anabasone (VI) followed from the fact that on reducing it with lithium aluminum hydride it gave (~)-anabasine, which was isolated as its pierate, m.p. 209-210".

As stated above, the structure of the substance of m.p. 229-231" as 5-01ydroxyimino)-3-pyridinevaleric acid 1-oxide (I) was confirmed also by its synthesis. As starting compound we used 2-nicotinoylglutaric diester (VII), which we prepared by Scheme A from nicotinic ester and glutarie ester in presence of sodium ethoxide [6]. By the deear- boxylation and hydrolysis of 2-nicotinoylglutaric ester we obtained 6 -oxo-3:pyridinevalerie acid (VIII). (VII) and the keto acid (VIII) were formed in better yield by working according to the procedure of J. Kovar (Scheme I , B, cf. [7]).

Scheme I A COOR

N "~ COCHCtt2CH~COOR "~ ( ~ / I ttOH

COOR _ _ _ ~ B COCH~COOR H" r

~ / (vii) + BrCHaCH2COOR~ /

COCH2CH~CH~COOR CCH2CH~CH2COOH //%~/ll

(viii) (iX)

Treatment of (VIII) with hydroxylamine under the usual conditions led to the formation of the hydroxyimino acid (IX), from which by oxidation with hydrogen peroxide in acetic acid we obtained the N-oxide, m.p. 229-231" and corresponding in composition to 5-0aydroxyimino)-3-pyridinevalerie acid 1-oxide (I). in all its properties this compound was identical with the product, m.p. 229-231", of the oxidation of anabasine. In examining the question of the order in which the processes of oxidation occur at the nitrogen arums in the anabasine molecule, we take their relative basic characters into aeeounL It is quite obvious that basic properties are more strongly marked in the piperidine nitrogen. Hence, the action of the oxidizing agent must be directed in the first place to this nitrogen atom. This view is supported by Our observation that by the action of 10% aqueous hydrogen peroxide on anabasine at ordinary temperatures a crystalline substance is formed which corresponds in composition and structure to 6-(hydroxyimino)-3- pyridinevaleric acid (IX). Identification was carried out by comparison with a synthetic sample and also on the basis of the infrared spectrum: UC= N = 1628 cm "x (cf. Table 1) . When this hydroxyimino acid is oxidized with 30%hydrogen peroxide in acetic acid, the above-described 6-0aydroxyimino)-3-pyridinevaleric acid 1-oxide (I) is formed.

In the papers of Sadykov and co-workers [8, 9] it is stated that in the oxidation of anabasine with 30% hydrogen peroxide, both in acetic acid and in absence of acetic acid, there was obtained an "amino acid" *unknown inchemical l i terature ' , which these authors called "6-amino-5-di-N-oxidopyridylvaler ic acid" and to which they attributed the structure (X) [9]:

CHCHsCH2CH~COOH

/~ NH2

~. o N

o (x)

As far as can be judged from the melting point and method of preparation of this compound, the authors were really dealing with 5 -0aydroxyimino)-3-pyridinevaleric acid 1-oxide (I), which differs in composition from the hypothetical compound (X) by two atoms of hydrogen. Unfortunately, in the article cited [8] the experiments are not described and there are no data confirming the composition and structure of the compounds obtained.

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E X P 2 R I M E N T A L

6- (Hydroxyimino) -37pyr id ineva le r ie Acid 1-Oxide fl)_ a. 40 g of anabasine was dissolved with cool ing in 300 ml of g l ac ia l ace t ic acid, and 160 ml of 34% hydrogen peroxide was added in one port ion. The mixture was heated for

24 hours at 70-80 ~ and was then diluted with water and vacuum-evapora ted until crystals began to separate. The

prec ip i ta te was fil tered off, and the f i l t rate was again evaporated. We obtained 26.0 g of a crystal l ine substance, m.p. 224-227 ~ (decomp.) . On prolonged standing, more crystals separated from the solution; the total yield of the acid (I) a t ta ined 68-72~ After recrys ta l l iza t ion from water, alcohol, or ace t ic acid or after repreeip i ta t ion from a lka l ine solution with di lute hydrochloric acid we obtained colorless needles, m.p. 229-231 ~ (decomp.) . The compound showed no opt ica l ac t iv i ty (in NaOH solution). Found: C 53.47; 83.46; H 5.24; 5.25; N 12.69; 12.67%.

C10H12NzO 4. Ca lcu la ted : C 53.57; H 5.40; N 12.49%. Found: neutral izat ion equivalent 22.9; 222.2; ca lcu la ted

224.2

6 - (Hydroxyimino)-3-pyr id ineva ler ic acid 1-oxide is sparingly soluble in water, alcohol, and the usual organic solvents (except N ,N-d imethy l fo rmamide) , but readi ly soluble in aqueous ammonia , in solutions of caustic alkal is , and in concentra ted acids (on heating). It does not form a picrate or hydrochloride.

Its e thyl ester was prepared by heat ing i t with alcohol and concentrated sulfuric acid and also by its react ion with a lcohol ic HC1 at room temperature; colorless crystals, m.p. 144-144.5 ~ (after recrys ta l l iza t ion from alcohol or water). The ester is readi ly soluble in chloroform and acetone. Found: C 56.87; 56.65; H 6.18; 6.17; N 11.26;

11.42%. C~HI~NzO 4. Calcu la ted : C 57.14; H 6.40; N 11.11%.

6 -Oxo-3 ,py r id ineva l e r i c Acid 1-Oxide [by th_e Hydrolysis of (I)]. A solution of 5.75 g of (I) in 20 ml of con- cent ra ted hydrochlor ic acid was refluxed for 7.5 hours (until HC1 ceased to be l ibe ra ted ) . The dark-colored solution was di luted with water to 120 ml, and the solution was brought to pit 4-5 with NaOH solution. The crystals that separated after some t ime were f i l tered off; weight 3.0 g, re.p. 224-227 ~ [unhydrolyzed acid (I)]. The fil trate was vacmma-evapora ted , the dry residue was boi led with a c e tone (100 ml), and the hot solution was f i l tered off. After five treatments the acetone extracts were combined, solvent was dist i l led off, 10 ml of water was added to the oily residue, and the solution was evaporated down to half bulk. On cooling, crystals of the N-oxide of the keto acid separated. Yield 0.6 g [22% on the amount of (I) that reacted], m.p. 165-167" (after recrys ta l l iza t ion from 60% me-

thanol), Found: C 57.27; 57.06; H 5.20; 5.21; N 6.45; 6.50%. C10HllNO 4. Calcula ted: C 57.41; H 5.30; N 6.70%.

The hydro chlor ide of 6 - o x o - 3 - p y r i d i n e v a l e r i c acid l - o x i d e was prepared by the evaporat ion of the hydrochloric

acid solution formed in the hydrolysis of (I). After recrys ta l l iza t ion .~f the dry residue from acetone we obtained colorless crystals. In the course of fusion at 120-130", HC1 was l ibera ted , and full transparency came at 161-163 ~ For

analysis we took an a i r -dry sample. Found: C 48.74; 48.60; H 4.96; 5.08; N 5.54; 5.52%. CI0HI1NO4HC1. Calcula ted:

C 48.89; tt 4.92; N 5.70%.

6- (Hydroxy imino) -3 -py r id ineva l e r i c Acid (IX). 120 ml of 10% hydrogen peroxide was added to 10 g of a n a - basine. The mixture was warmed to 30*. After i t had stood for e ight days at room temperature , the solution became yeUowi;h and had a lmost lost its opt ica l ac t iv i ty . After di lut ion with an equal volume of water, the solution was vacuum-concen t ra t ed . This operat ion was repeated several t imes, the solution was then evaporated to dryness, and the syrupyresidue was dissolved in a l i t t l e water. The crystals prec ip i ta ted on scratching the sides of the vessel were separated. After reerys ta l l iza t ion from water and then from toluene we obtained co!orless needles, m.p. 161-163 ~ The compound did not rotate the plane of polar izat ion (in a lka l ine solution). Found: C 57.33; 57.31; H 5.72; 5.67;

N 13.26; 13.29%. CIoH~NzO 3. Ca lcu la ted : C 57.68; H 5.81; N 13.46%.

After a long t ime (2.5-3 weeks) a further 0.7 g of crystaUine substance separated from the solution. The total

yield of unpurified product was 42% of the ca lcu la ted amount.

Oxidat ion of 6 - (Hydr0xy imino) -3 -py r id ineva l e r i c Acid (IX) to the N-Oxide (I). 10 ml of g lac ia l ace t ic acid and 2.5 ml of 30% hydrogen peroxide were added to 0.7 g of (IX),m.p. 158-159". The mixture was heated at 75-80* for 22 hours, and then by the usual t rea tment (dilution with water; d is t i l la t ion at reduced pressure) we isolated 0.45 g

of a substance of m.p. 224-227 ~ After crys ta l l iza t ion from water we obtained 0.4 g of product of m.p. 229-231 ~ (decomp.) , undepressed by admixture of 6 - (hydroxy imino) -3 -pyr id ineva le r i c acid 1-oxide prepared by the oxidat ion of anabasine.

(~t)__~76-A__mino-3-pyridinevaleric Acid Lactam (VI)t A flask fi t ted with stirrer, reflux condenser and thermo- mete r was charged with 3.5 g of 6 - (hydroxy imino) -3 -pyr id ineva le r i e acid 1-oxide and 70 ml of g l ac ia l ace t ic acid, The mixture was heated up to 110", when comple te dissolution occurred. With constant stirring, 10 g of zinc dust was

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added carefully in small portions. The temperature then rose to 115 ~ The mixture was boiled for eight hours with

stirring and was then diluted with an equal amount of water�9 Unchanged zinc was separated, and the solution was carefully made alkaline with aqueous ammonia and extracted with chloroform. The extract was dried with anhydrous potassium carbonate and solvent was distilled off; we then obtained 2.1 g of a colored crystalline subatance. After crystallization from nonane we obtained colorless needles, m.p. 134-136". The compound was somewhat soluble in ether, and on slow evaporation of its ethereal solution crystals of m.p. 137-138.5" were formed. Found: C 68.14; 67.86; H 6.71; 6.85; N 15.83; 15.88~ C10H~N20. Calculated: C 68.18; H 6.82; N 15.90%.

(.~)-Auabasine from (:~)- 5-Amino-3-pyridinevaler ie Acid Lactam. A solution of 1.35 g of the (:~)-lactam (m.p. 136-138") in 50 ml of tetrahydrofuran was added over a period of two hours to a vigorously stirred suspension of 1.0 g of lithium aluminum hydride in 250 ml of dry tetrahydrofuran. The mixture was boiled for five hours and was then left for twelve hours at room temperature. ~ne excess of lithium aluminum hydride was decomposed with 200 ml of wet ether, the mixture was filtered, and the aluminum hydroxide was washed with ether, which was then added to the filtrate. The solution was vacuum-evaporated, and 40%o NaOH solution was added to the residue; the organic layer was extracted with ether. The extract was dried with anhydrous potassium carbonate, solvent was distilled off, and there remained an oily residue, which consisted of a mixture of (:~)-anabasine and unchanged lactam. Separation of the mixture by its conversion into picrates (the picrate of the lactam is soluble in water) gave 1.25 g (35%) of a substance of m.p. 200-207*. Reerystallization of the picrate from water did not raise the melting point. For purifica- tion, 0.5 g of the pierate was dissolved in 5 ml of N,N-dimethylformamide, and water was added to the solution until a precipitate formed. We isolated 0.37 g of (~)-anabasine dipicrate, m.p. 209-210". The literature [10] gives m.p. 213-214". Found: C 42.41; 42.57; H 3.98; 3.10%, CIoHI4Nz. 2C6HsNaO 7. Calculated: C 42.61; H 3.25%.

Ethyl (~)-5-Amino-3-pyr id inevalera te Dihydrochloride. ( :~)-5-Amino-3-pyridinevaleric acid laetam was heated for a short time with alcoholic HC1, and subsequent precipitation with ether gave a compound of m.p. 198.5- 200* (after several crystallizations from alcohol). Found: C 48.60; 48.76; H 6.68; 6.74; C1 23.70; 23.96%.ClzHtaN~O 2. �9 2HC1. Calculated: C 48.82; H 6.83; C1 24.02~

.(+)-5-Benzamido-3-pyridineva!eric Acid (XI). The oxidation of N-benzoylanabasine with potassium permanganate was carried out under the conditions described by Men'shikov, Losik, and Orekhov [5]. It was noted that the benzoic acid formed in small)amounts in the course of the oxidation makes the isolation of the acid (XI) in the crystalline state difficult. The solution obtained after evaporation was acidified to Congo Red, extracted with ether, and then again acidified until crystals of the acid (XI) were precipitated. From 20 g of N-benzoylanabasine we obtained 4.9 g (22%) of 5-benzamido-3-pyr idinevaler ic acid, m.p. 141-143". After reerystallization from water the acid had m.p. 145-146"; [a] D + 9.3* (N,N-dimethylformamide, p = 7.13). The literature [5] gives m.p. 146".

( - - ) - 6-Amino-3-pyr id inevaler ic Acid Lactam. 5-Amino-3-pyridinevaler ic acid hydrochloride (1 g), prepared by the hydrolysis of the benzamido acid (XI), was heated for 4.5 hours at 158-162". 5 ml of water was added to the

glassy mass formed, and the solution was neutralized with sodium bicarbonate and extracted with chloroform. The extract was dried, solvent was distilled off, and we obtained 0.34 g of a crystalline substance, m.p. 138-146". After being crystallized from nonane the substance had m.p. 146-147"; [Ct]D - 61" (chloroform, p = 2.34). The literature [5] gives m.p. 147-147.5". A mixture with the laetam prepared by the reduction of S-(hydroxyimino)-3-pyridinevaleric acid 1-oxide melted over the range 136-147".

Diethyl 2-Nicotinoyl~lutarate (VII). A mixture of 12.1 g of finely divided sodium, 85 ml of benzene, and 24.3 g of absolute ethanol was stirred until the sodium was completely dissolved. A mixture of 33.2 g of ethyl nicotinate and 82..5 g of diethyl glutarate was added to the solution over a period of 30 minutes at 25-30*. The temperature was brought Io 80*, and the solution was stirred further for 90 minutes. The solution was then cooled to 10", and 135 ml of 10% hydrochloric acid was added at not above 15-20". A thick mass then formed, and, with further addition of hydrochloric acid, this formed two liquid layers. This two-phase system was saturated with sodium bicarbonate and extracted with ether. After drying the extract with anhydrous magnesium sulfate, distilling off the solvent, and distilling the residue, we obtained diethyl 2-nicotinoylglutarate as a colorless oil, b.p. 173-175" (2 ram), which gave a positive reaction with ferric chloride [6]. For analysis we took the fraction of b.p. 147-147.5" (0.1 mm); n~) 1,4995, obtained in the redistillation of this oil. Found: C 61.58; 61�9 H 6.62; 6.48%. ClsHi91qO s. Calculated: C 61.42; H 6.53%o.

5-Oxo-3-pyridinevaler ie Acid (VIII)_. A mixture of 18.0 g of diethyl 2-nicotinoylglutarate and 90 ml of 10% sulfuric acid was refluxed for 21 hours. When the solution was cool, concentrated aqueous ammonia was added drop- wise. The precipitate that then formed was separated, and recrystallization from water and drying in air gave 8.6 g of product, m.p. 121-123", undepressed by admixture of a sample of 5-oxo-3-pyridinevaler ie acid (VIII) given to us by Kovar (hemihydrate, m.p. 120-122~ When dried at 100-110", our acid melted at 165-170"; this was probably due to the decomposition of the crystal hydrate.

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5-(Hydroxyimino)-3-pyridinevaleric Acid (IX). A solution of 1.9 g of the keto acid (VIII), 1.65 g of KOH, and 1.0 g of hydroxylamine hydrochloride in 20 ml of water was heated for seven hours at 80 ~ When cool, the solution was filtered from the small precipitate and acidified with dilute hydrochloric acid. The precipitated crystalline oxime of the keto acid was separated; weight 1.75 g; m.p. 158-160 ~ After recrystallization from water and then from toluene we obtained colorless crystals, m.p. 161-163 ~

5-(Hydroxyimino)-3-pyridinevaleric Acid 1-Oxide (I). A mixture of 3.5 g of the oxime prepared in the pre- ceding experiment from the keto acid, 40 ml of acetic acid, and 2 ml of 30% hydrogen peroxide was heated for 18 hours at 75-80 ~ On dilution with water and removal of solvent we isolated 2.3 g (61%) of the N-oxide (I), m.p. 228- 231 ~ (from water). Found: C 53.72; 57.47; H 5.43; 5.30; N 12.75; 12.74%. C10H~N204. Calculated: C 53.57; H5.40; N 12.49%.

A mixture of this substance with the 6-(hydroxyimino)-3-pyridinevaleric acid 1-oxide obtained by the oxidation of anabasine melted at 229-231 ~

The authors find it a pleasant duty to thank L Kovar (Prague) for the sample of 6-oxo-3-pyridinevalerie acid and for describing the method by which it was prepared.

SUMMARY 1. When anabasine is treated with 30% hydrogen peroxide in acetic acid, both the pyridine and piperidine parts

of the molecule of this alkaloid are oxidized with formation of 5-(hydroxyimino)-3-pyridinevaleric acid 1-oxide, whose structure was established by studying its reactions and comparing it with a synthetic sample.

2. Reduction of 5-(hydroxyimino)-3-pyridinevaleric acid 1-oxide gives ( ,~)-5-amino-3-pyridinevaleric acid laetam.

3. The action of 10% aqueous hydrogen peroxide is directed at the piperidine nitrogen atom of the anabasine molecule; as a result of the subsequent transformations the piperidine nucleus undergoes cleavage with formation of 5-(hydroxyimino)-3-pyridinevaleric acid.

L I T E R A T U R E C I T E D 1. V.K. Zvorykina, F. D. Alashev, and Ya. L. Gol'dfarb, Izv. AN SSSR. Otd. khim. n. 788 (1958). 2. A .G. Davies, Organic Peroxides, London, Butterworth, p. 55 (1961). 3. K. Kahr and C. Berther, Chem. Bet. 9_33, 132 (1960); O. L. Lebedev and S. N. Kazarnovskii, Zh. obshch, khimii

3_.~0, 1631 (1960). 4. E. Ochiai, J. Organ. Chem. 1__88, 534 (1953). 5. a) G. Men'shikov, I. Losik, and A. Orekhov, Khim.-farm. prom. 7 (1934); b) G. Menschikoff, J. Lossik, and A.

Orechoff, Ber. 67, 1157 (1934). 6. L C. Shivers, M. L. Dillon, and C. R. Hauser, J. Amer. Chem. Soc. 69.9, 119 (1947). 7. M. Ferles and J. Jizba, Chemic Pyridinu, Praha, sir. 440 (1957). 8. A.S. Sadykov and ~ K. Karimov, Uch. zap, Leninabadskogo gos. ped. instituta, No. 10, p. 119 (1958). 9. A.S. Sadykov and O. S. Otroshchenko, Chemistry, Technology, and Application of Pyridine and Quinoline [in

Russian], Riga, p. 89 (1957). 10. F. Sp~th and L. Mamoli, Bet. 6__99, 1082 (1936).

A l l a b b r e v i a t i o n s of p e r i o d i c a l s in the a b o v e b i b l i o g r a p h y are l e t t e r - b y - l e t t e r t rans l i t er -

a t i o n s o f the a b b r e v i a t i o n s as g iven in the o r ig in a l R u s s i a n j o u r n a l Some or all of th is per/-

o d i c a l l i t e ra ture may we l l be a v a i l a b l e in Engl i sh translat ion. A c o m p l e t e l i s t o f the c o v e r - t o -

c o v e r E n g l i s h t r a n s l a t i o n s appears at the back o f th i s i s s u e .

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Documents

Oxidation of anabasine with hydrogen peroxide