C.C.: OVERBERGER AND J. J. MONAGLE
44iO [ CONTRIBL'1'ION FROM
THE
I>EPAKTXENTO F CHEMISTRY, POLYTECHNIC ISSTITUTE
Vol.
7s
O F BROOKLYN]
Azo Compounds. The Preparation and Oxidation of 3,7-Diphenylhexahydro-1,Z-diazepine BY
c. G. OVERBERGERA N D JOHN J. f i f O N 4 G L E ' RECEIVEDFEBRUARY 6, 1956
Compound 11, 3,7-diphenylhesahydro-1,2-diazepine,has been prepared and characterized. Attempts t o synthesize have resulted in the formation of 111, the azine of 3-methyl-2-cyclohexencompound I , 3,7-dimethylhexahydro-1,2-diazepine, I-one (111). Oxidation of I1 with bromine in aqueous ethanol in acid solution gave 6-bromo-6-phenylvalerophenone( V I I ) . The structure of \-I1 mas demonstated by dehydrohalogenatioii to give VIII. .Alkaline permanganate oxidation of VI11 gave benzoic acid and 0-benzoylpropionic acid. Oxidation of VI1 with neutral permanganate in aqueous acetone gave the diketone IV. Reduction of VI1 over palladium-on-calcium carbonate gave the monoketone IX which was identical with an authentic specimen.
-1s part of our general program to synthesize cyclic azo compounds which would be capable of giving moderately active biradicals in solution, we have attempted the synthesis of I and 11. This paper reports the successful synthesis of I1 and unsuccessful attempts to prepare I. I n an attempted synthesis of I , heptane-2,6-dione3 was treated with hydrazine to give in sly0 yield the azine of 3 methyl-2-cyclohexene-1-one (111), instead of the expected cyclic azine. A wide variety of reaction conditions were tried without successfully changing the course of the reaction, some 45 variations being attempted. Thus I11 was also obtained in 19%
C6Hs
I
I
c=o
c=o I
.. \C/
IV was prepared in 72% .yield by the method of Augersa using a modification of the method of Fuson and Walkersbfor the preparation of dibenzoylbutane. The diketone IV was treated with hydrazine hydrate and a catalytic amount of acid to give the cyclic azine V in 95y0 yield. The reaction was carried out in relatively dilute solution (0.16 nl) in accord with the general knowledge of the Ruggli dilution principle.6 The conditions of reaction and catalyst concentration are important to obtain the high yield realized. Polymer formation is the principal side reaction. Reduction of the azine to the cyclic hydrazine I1 was carried out in 66% yield with lith\ ium aluminum hydride. This reagent has reCH3 111 CH3 cently been reported for the reduction of a hydrazine linkage to a saturated hydrazine, although to yield from the reaction of heptane-2,6-dione with date there are relatively few examples of this inhydrazine in acid solution. teresting reduction7"ib with azines. The question A comparison of I11 with the azine prepared remained as to whether the structure of 11 might from a known sample of 3-methyl-2-cyclohexen-l- possibly be the six-membered 1-amino compound, one and hydrazine hydrate4 demonstrated that the VI. The infrared spectrum was not definitive since compounds were identical, that is, no depression of the melting point was observed by a mixed melting point determination and their infrared spectra were identical. It was apparent from these results that cyclization of the diketone via an aldol condensation was SH1 1-1 much too facile and that i t would be impossible to prepare I via the azine route. the phenyl peak in the 6.25 p area sometimes Preparation of I1 was accomplished according to masks the NH2 bending frequency in this region. the scheme I n the 3 I.L area the N H frequency would be similar to an NH2 group and a distinction cannot be made. ( 1 ) l h i s i s thc 1 9 t h in a series of papers concerned with thc prejwraThe p k T ~of I1 was determined to be 5 X in tinn and decomposition of azo compounds. Fur the previous pager in this series see C. G. Overherger, S. R. Byrd and K. R . Ilesrobian, ethanol-water solution. Consequently V I was T H I S J O U R N A L , 7 8 , 1 g f i l (1956). synthesized and shown to be different from I1 in /'
( 2 ) This paper comprises a portion of a thrsis presented b y J. J . Ilonagle in paitial fulfillment of t h e requirements for t h e degree of Doctor of Philosophy in t h e Graduate School of t h e Polytechnic Institute of Brooklyn. (3) C. G. Overberger, P. Huang, T. Gihh. J r . , S. Chibnik and J. J . Rlcmagle, THISJ O I T R N A T, 74 ( 4 ) I < . -ellowtinged solid. Thorough washing with water removed the )-ellow color. The wet solid was pressed out on a Buchner funnel and then immediately dissolved in 300 ml. of methj-lene chloride. The water which separated was removed, and the remaining solution was dried over magnesium sulfate. The yellow aqueous solution was extracted with five 50-ml. portions of methylene chloride, and the extracts were combined and dried over magnesium sulfate. The methylene chloride solutions were filter? 1 :md evaporated separately in ati air stream. Thc solutioii containing the yellow solid deposited 11.7 g. (W)%, hisetl on bromoketone) of white solid tinged with yellow, m . p . 85-99'. Recrystallization of this solid from a chlorciforrn petroleum ether ( b . p b 28--38O) solution raised the melting point to 116.8-117.2 . Yields of purified material averaged 41%. This material gave a positive test with the "4dinitrophenylhydrazine reagent.'s Calcd. for C17H1,BrO: C, 64.36; H, 5.40; Br, 25.19. Found: C, 64.27; H , 5.58; Br, 24.95. Hydrogenolysis of 5-Bromo-l,5-diphenyl-l-pentanone. The bromoketone VII, 2.0 g. (0.0063 mole), was suspended in 80 ml. of ethanol and hydrogenated at 40 Ib. pressure n i t 1 1 0.4 g. of palladium-on-calcium carbonate. IVheri thc rate of hydrogen uptake had decreased, the mixture was filtered to remove catall-st. The solid on tlie filter paper was mashed with several portions of ethanol, and the 1 combined with the filtrate. The volume of tlie was reduced to about 20 ml. by warming under pressure. The remaining light green solution was coolctl a t Drl- Ice temperature and gave 0.72 g. (18.37GI of, 1 ,Zcliplieiiyl-1-pentatlone, 11i.p. 42.8-44.8"; m.p. (ixitiie"i -i 1.4-78.6" (n1.p. 47', ketone; oxime, 81-82).8 -4mixed melting point of this material with :in autlieiitic sample, 1,5-diphenyI-l-pentanone( I S ) , m.p. 12..8-4l.X, melted a t 42.4-13.8'. Comparison of the infrared spectra demonstrated that tlie compounds were idcnticnl. Preparation of Cinnama1acetophenone.-From .3i g . (1.3 moles) of sodium liydroxide in S'K1 1111. of watcr ar~tl 4% ml. of ethannl, 132.1 g. (1.1 moleq) of ~ i c e t o p i ~ e l ~ o ~ l c and 145 g . ( 1. I moles) of ciiiriamaldeliyde, tlicre \v'Li 01)tained 244 g. of product, m.p. 91-98", Recrystxllizatiotl from a mixture of 530 ml. of ethanol and 350 nil. o f tncthyl acetate g?ve 188.4 g. (73%) of >-ellow crystalline solid, m.p. 100.4-102.0" (reported," no yield, m.p. 102"). Preparation of 1,s-Diphenyl-1-pentanone (IX).--The ketone was prepared from cinnamalacetophenone h y the method of Borsclie.8 The procedure yielded a liquid, 11.1). 138-145' (0.25-0.3 xnm. I , n Z 51.5659 ~ no yield, b . p . 225-226' (16 m m . ) , m.p. 17" from petroleum ether ( I 3 . p . 2s-38") g:r the ketone, rri.11. 42..8~-41.8". Bromination of 1,s-Diphenyl-1-pentanone .-Tc ;I 5olutiriii of 8.5 g. (0.035 mole) of the ketone in 150 ml. of chloroform TKLS added j . 7 g. (13.033 mole) of bromine over a period o f 1.5 Iir. The temperature climbed from 80.,5to 23' during the course of the reaction. The orange brominc color disappeared very slowly a t the beginning of the reaction, then inore rapidly until at approximately the point of half addition the solor disappeared immediately after addition. A strong evolution of hydriigen bromide w,ts noted as tllc reaction progressed. As the reaction approached corrlpletion, the bromine color ~r-asnot discharged. ~ ~ _ _ ~
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