3126
w.D. KUMLER,R . BOIKESS,P.BRUCK,A N D s. WINSTEIN
syn-8-chlorodibenzobicyclo [ 32 . 1j octadien-emu-2-01 ( m .p. 137.5138.5') ( X ) was depressed. The infrared solution spectra of the two compounds taken in carbon disulfide showed marked differences.' Anal. Calcd. for Cl6HK10: C , 74.85; H, 5.08. Found: C, 75.02; H, 5.07. syn-8-Chlorodibenzobicyclo[3.2.l]oc tadien-endo-2-yl Acetate (VIII).--.I\ solution of 263 mg. (1.025 mmoles) of \-I1 in acetic anhydride and several drops of concentrated sulfuric acid was heated on a hot plate for 5 min. The solution was poured slorvly into water and extracted with two 50-nil. portions of chloroform. The reaction mixture was dried over anhydrous sodium sulfate, filtered, anti the solvent was removed by rotary evaporation. The oily residue was dissolved in carbon tetrachloride and subjected t o column chromatography on a column which was packed with 100 g. of Woelm neutral alumina in carbon tetrachloride. The ciilumn was eluted with the following solvents: carbon tetracliloride, chloroform, and 10cz ethyl acetate in chloroforn:. The first fraction containing ethyl acetate yielded 253 tng. (835%) of \*I11 melting a t 183.5-138". Recrystallization from ethanol gave a melting point of 136-137'. This compound when compared with I\- showed different infrared solution spectra in carbon disulfide. A mixture melting point for the two isomers was depressed. An analysis was obtained in this laboratoryg for a compound but synthesized in a believed to be the syn-chloro-endo-acetate, different manner. This melted a t 14&146°. When a mixture melting point was taken of the two, the mixture melted a t 138.5111.5'. X remelting point of the resolidified mixture was 135136.7'. Tliere was a marked difference between the infrared spectra of tlie two compounds from 13-25 p when the spectra were taken in potassium bromide pellets. When the two samples were each dissolved in carbon disulfide, their solution spcctra were shown to be identical from 2-25 p . Crystalline modifications were observed both in the syn-chloro-endo-alcohols and acetates. Products from the [3.2.1] ring system were always compared in the above manner. The Permanganate Oxidation of syn-8-Chlorodibenzobicyclo[ 3 . 2.l]octadien-endo-2-01 (VII) to syn-8-Chlorodibenzobicyclo[3.2.l]octadien-2-one (IX).-Compound \.I1 (149 mg., 0.580 mrriole) was subjected to the permanganate oxidation procedure previously reported for tlie s~n-8-chloro-e.~o-2-alcohol.* The product, 130 tng. (87' of a white crystalline compound, showed a melting point of 121-122%". .I mixture melting point with known syn-8-chlorodibenzobicyclo [3.2.1]octadien-2-one (IX)* showed no depression. Infrared spectra of both samples were identical.
VOl. 86
The Epimerization of syn-8-Chlorodibenzobicyclo [3 2 . 1 J octadien-emu-2-yl Acetate (IV) to syn-8-Chlorodibenzobicyclo[J .2.1]octadien-endo-2-yl Acetate (VIII).---A mixture of 1.54 g. of i0C.; perchloric acid (1.54 rnmoles), 10 ml. of glacial acetic acid, and 438 mg. (1.46 mmoles) of IT' was heated a t 85' for 4 h r . The solution was then poured into 200 ml. of water and extracted with two 100-ml. portions of benzene. The organic layer was washed with a Si'; sodium bicarbonate solution and then twice with water. The benzene extract was then dried over anhydrous sodium sulfate, filtered, and the solvent was removed by rotary evaporation, leaving 432 mg. of a clear yellow oil. A spectrum of the crude product was identical with t h a t of the endu-acetate 1.111. The product was recrystallized froni petroleum ether i b . p . 60-70") twice, and 114 mg. of a compound melting a t 141142' was obtained. .I mixture melting point with a sample of VI11 showed no depression. A solution spectrum of the product in carbon disulfide was taken from 2-25 p and was found t o be identical with t h a t of \-III. The mother liquors from the recrystallizations were combined and subjected to elution chromatography on an alumina column packed with 10 g. of LVoeltn neutral alumina. The chromatogram was eluted with petroleurn ether ( b . p . 60-70"),carbon tetrachloride, and cliloroform. The fractions eluted with chloroforin (217 mg.) yielded upon recrystallization 120 mg. of a compound melting a t 121-139' and having a solution spectrum identical with that of \.III. T h e impurity seemed, from the crude infrared spectrum, t o be a small amount of the hydrolysis sy)z-8-clilorodibenzobicyclo [3.2.1]octadien-endo-2-01 product (T'II). LVlien the tnotlier liquors mere combined and the solvent removed by rotary evaporation, an oil weighing 23 mg. was obtained. The oily product was dissolved in 10 nil. of acetic anhydride, and 2 drops of concentrated sulfuric acid was added. The mixture was warmed for several minutes and then poured slowly into water. The aqueous mixture was extracted twice with benzene, and the combined organic layers were decolorized with S o r i t and dried over anhydrous sodium sulfate. When the solvent was removed by rotary evaporation, 27 ing. of a conipound having a melting point of 121-135° was obtained. Upon recrystallization from petroleum ether ( b . p . 60-70"), 1 5 mg. of a compound, m.p. 128-110", was recovered. .In infrared spectrum of this compound showed it t o be 1.111. The crude yield of \-I11 was 5gC;.
Acknowledgments.-The authors are indebted to the Kational Science Foundation and to the Air Force Office of Scientific Research for generous support of this research.
[CONTRIBUTION FROM THE DEPARTMEST OF PHARMACEUTICAL CHEMISTRY, SCHOOL O F P H A R M A C Y , c N I V E R S I T Y O F CALIFORNIA, SATFRAXCISCO, C A L I F ,ASD CONTRIBUTIOS NO 1631 FROM THE DEPARTMENT OF CHEMISTRY, UNIVERSITY OF CALIFORNIA, LOS h N G E L E S , CALIF.]
Dipole Moments, Configuration, and Conformation of Tricyclo [5.1.O.O'~'j]octane Derivatives and Related Compounds' BY \V. D. KUMLER, ROBERTBOIKESS,P. BRUCK,A N D S.WINSTEIN RECEIVED FEBRUARY 17, 1964 Tricyclo [b.1 .0.03.5]octane(\.I), 4,4-dibromotricyclo[.5 1 . K O 3 i]oct:~ne ( \ - ) , and 4,4,8,8-tetrabroniotricyclo[6.1.0.03,5]octane (111i have been prepared. The dipole tnornents of these compounds as well as those of norcarane ( \ . l I I ) , A3-norcarene (I\'), 7,7-dibromobic~clo[4.l.~l]heptane ( \ . I I ) , A3-~.7-dibroniohicyclo[1.1.0]heptene [ I1 ), l,l-c~.clohexadiene( I ) , cyclohexene, and cyclopentene have been measured. Zero dipole moment for I11 proves its configuration is trans and the six-membered ring has a relatively flat conformation. The methods of preparation indicate a trans configuration for \-I and \- and the dipole moment values favor nearly flat conformations for the six-membered rings in these compounds. Cyclohexene and cyclopentene were found t o have dipole moments of 0.21 D . which are considerably smaller than most values in the literature. Sorcarane has a moment of 0 44 11. The evidence indicates the central ring is relatively flat when either cyclopropane or olefinic groups are tin opposite sides of a six-membered ring.
In the course of another study2 it was necessary to determine the configurations of the bisrnethylene adducts c'f 1.4-cyclohexadiene ( I ) . One of the bis( 1 ) Presented a t the l4Pnd National hleeting of the American Chemical Srmety, .Atlantic C i t y . N J . . S e p t . !i-l-l, 1082, .4bstracts, p 8 0 0 ( 2 1 I' H r i i c k a n d I< Aitike\.;, unpublished work
adducts can be derived from the crystalline tetrabromide3 111, tlie bisdibrornocarbene adduct of l,.l-cyclohexadiene. As a guide to configuration, the dipole Of the was and in (3) (a) K. H o f m a n n , rf a l . . J . A m . Chem. S O L . ,81, 992 (1959): Winstein and J. S o n n e n b e r g . h d , 83, 3235 (1961).
(b) S.
3127
TRICYCLO [5.1. o . 0 3 , 5 ] O C T A N E DERIVATIVES
Aug. 5 , 1964
TABLE I
SUMMARY OF DIPOLEMOMENTS AND RELATED DATA B
a
"I
(1
2 27382d
111, trans
1,13891 0 21233
-0 69932
-
*%I
0.17074
PZo
PE,
72.36
60 24" 65 00'
li
0 77
Est a t polariz
121
p
0 0
43 79" 2 1 9 f O 0 1 6 0 2 1 2 f 0 0 1 45 62' 0 8 044 36950 35 54 30 86" 0 48 1 91754" 1 4 7 0 4 3 0 32162 - 28750 \'I11 30 79' 52597 139 91 47 14" 2 13 zk 0 01 6 0 2 O i i O 01 2 27479$ 1 14151 1 94731 - 60149 V, trans 49 46' 1 0 013 31697 34 29 32 97" 0 25 1 46772 0 23940 - 40788 1 91789' V I , trans 32 22* 33 14' 28 0 7 21 35116 28 84 27 21e 35116 - 22154 1 91768e 1 46881 2; 20' 2 i 03c 0 4 21 25 34392 23 42 22 11" 13956 - 17321 1 92042e 1 46778 21 59* 22 13c 27 7; 26 14" 28 12 13 31664 1 9173ge 1 46900 24472 - 28891 I 26 i ; * 26 14' 46 1 1 40 35997 33 68 29 30" 1 91799" 1 46889 34798 - 36829 IV 30 33' 29 5ZC 49928 120 75 44 35" 1 9 3 + O 01 6 0 1 8 i f O 01 2 2719gd 1 13448 1 79543 - 58183 I1 44 83* €1, dielectric constant; V I , specific volume; a,slope of €12 - wz plot; p, slope of Y I Z - w2 plot; &, specific polarization; P20,molecular polarization; PE,, electronic polarization; p , dipole moment; w , weight fraction. From refractive index of pure liquid. Measured in benzene a t 6 From atomic refractions a From refractive index of solution. 25'. 8 Measured in heptane a t 25". 2 27217~ 1 14122 2 21213
VI1
58781
57975
141 43
0
the course of this work measurements were made on a number of related compounds and still other materials for comparison. The results of this study are presented and discussed in the present article.
I
I11
11
IV
VI
V
Results The dipole moment values in Debye units and other data are given in Table I. All values were obtained using the HalverstadtKumler equation and method of c a l c ~ l a t i o n . ~hIo3av1 P20
=
+ + + (VI
(€1
2)2
"',, €1
- 1
ments were calculated using an I B M 1620 computer. In case of the compounds with dipole moments above 1.5 D . , the accuracy of the determinations as indicated by the scatter of points on the e12 - w2 line was within 0.01 to 0.02 D . The accuracy with compounds with moments less than 0.5 D . is less and here the atomic polarization is a limiting factor and this has been estimated in each case usually by comparison of the atomic polarization of analogous compounds. (4) I. F . H a l v e r s t a d t a n d (1012).
a'. D.
K u m l e r , J . A n i . Chrm. S O L . .64, 2988
Dipole Moments, Configuration, and Conformation.The pure crystalline tetrabromide 111, m.p. 201-20Go, gave a P?, value of 72.36 and a P E 2value of 60.24 from the refractive index of the solutions. X dipole moment of 0.ii D. is calculated making no allowance for atomic polarization. From atomic polarization values of 3 for ethyl bromide, 6.1 for P-dibromobenzene. and 6.2 for trans-l,4-dibromocyclohexane,j an atomic polarization value of 12 may be estimated for tetrabromide 111. On this basis, the derived dipole moment for 111 is zero. The vanishingly small value of the dipole moment of I11 proves that this compound has the two cyclopropane rings in a trans rather than cis relationship. This may be seen more clearly by examining dipole moment values estimated for different conformations of both cis and trans isomers of 111. To make these estimates it is helpful t o consider the dipole moments of T,Tdibromonorcarane6 (VII) and norcarane (VIII) itself. The direction of the dipole between the six-membered and the three-membered ring in norcarane structural types is of concern in calculating the theoretical dipole moment of the different conformations of compounds discussed in this paper. The angle to be considered is that between the direction of this dipole and the plane of the three-membered ring. One extreme possibility is that the dipole between the two rings is in the plane of the bonds between the CH2 carbons in the six-membered ring attached to the carbons common to both rings. This gives an angle of 75' between it and the plane of the cyclopropane ring. The other extreme is that the dipole is along the line connecting the centers ( 5 ) W Kevestrov, F. A . XIeijer, a n d E . H e v i n g a , Rir. / i n ; ' c h i i n . . T13. 718 (1954). (6) IT. von E. Doering a n d A K Hoffman. .I. A i i i C h r w Sur . 1 6 , 6 1 6 2 (1'354).
W. D. KUMLER,R . BOIKESS,P. BRUCK,AND S.WINSTEIN
3128
TABLE I1 CONFIGURATIONS, CONFORMATIOSS, ASD CALCULATED DIPOLEMOMENTS Con formaConfiguration
tion sixmembered ring
Angle between dipoles
Dipole -momentCalcd. Obsd.
I11
lrans
Boat
154'
0.85
111
lrans
Flat
180'
0.0
I11
cis
cis-Boat
111
cis
trans-Boat
111
cis
VI
90
4.20
109'
2.76
Flat
59'
3 65
lrans
Boat
130'
0.37
VI
lrans
Flat
180'
0.0
V
Irans
Boat-Br Iran5
172'
1.67
V
trans
Boat-Br cis
172'
1.67
V
lrans
Flat
122'
1.92
IV
cis-Boat
130'
0.35
IV
Irons-Boat
145'
0 30
IV
Flat
175'
0 23
I1
cis- Boat
77'
2.17
I1
Irons-Boat
157'
1.92
I1
Flat
117'
2.02
I
Boat
135'
0 16
I
Flat
180'
0 0
0.0
0.13
2.07
0.40
1 87
0 13
of the two rings which gives an angle of 5 ( 3 O between it and the plane of the cyclopropane ring. I t is likely that the dipole is in a direction in between these two extremes and one can get an indication of where it is by considering 7,i-dibromonorcarane (VII). For 7,i-dibromonorcarane (VI1j the P2, of 141.43 and a P E , of 43.79 from the refractive index of the solutions give a moment of 2.19 D. neglecting atomic polarization. Assuming an. atomic polarization of 6, the moment is calculated to be 2.12 D. I t is clear that the resultant of the two C-Br dipoles in this compound must be in the plane of the three-membered ring. This resultant is calculated taking the value of the C-Br dipole as the moment of bro~nocyclopropane,~ 1.7 D. ( 1 .GO D , ) , and the angle between the G B r dipoles as 1 1 2 O , the same as that between the C-Cl dipoles in ( 7 ) 1 I ) . I
