Yol. 7s
COMMUNICATIONS 'TOTHE EDITOR
417U
A STANDARD OF ABSOLUTE CONFIGURATION FOR OPTICALLY ACTIVE BIPHENYLS' Sir :
argument applies with a t least equal force to the transition states. Models reveal that I I a is much more stable than ITb. In IIa, the angle between The establishment of the absolute configuration the plane defined by (2.15-C.14-C.9 and that deof D-tartaric acid by the anomalous diffraction fined by (2.14-C.9-N is close to 0'. In IIb, howtechnique2 provides the basis for the unique as- ever, this angle is close to 60'. Thus if I I b were signment of stereochemistry to any center of car- the intermediate, the five-atom ring ((2.15, C.14, bon atom asymmetry. Heretofore, no basis has '2.9, N, (2.16) would have to be severely puckered. existed for such assignments in the case of sub- Even when the resultant release of non-bonded stances possessing axial asymmetry, e.g., optically interaction is laken into consideration, an interactive biphenyls. %'e should like to point out planar angle of GOo would be intolerables when the that the configuration of the biphenyl system in system has available the Baeyer-strain-free alterphenyldihydrothebaine (111) can be related op- native Ira. The biphenyl system of phenyldierationaZZy3 to the configuration of thebaine ( I ) . hydrothebaine therefore has the absolute configuraConsequently, since the absolute configuration of tion shown in TII, and the simpler bicyclic derivathe morphine thebaine group of alkaloids is now tives (e.g., the methines, isomethines, phenylknown,5 the absolute configurations of the axially tetrahydrothebaimine and the nitrogen-free degasymmetric systems in 111, and in a series of its radation products6) all have the absolute conderivatives of the general formula IV, are estab- figuration IV. The series provides a standard of absolute configuration for optically active bilished. Thebaine (I) is converted by phenylmagnesium phenyls. bromide to a mixture of two phenyldihydrothe(8) Compare t h e interplanar angle of 1 7 ' in t h e pyrrolidine r i n g of baines (111) which differ only in the configuration hydroxyproline [J Donohue a n d K N Trueblood, A d a Crysf, 6, 419 (1952) ] a t the asymmetric carbon a t o m 6 DEPARTMEVT OF CHEMISTRY vNIVERSITY O F SOETHERX CALIFORNI-4
Los AXGELES7, CALIFORNIA
JEROME
A BERSOS
RECEIVED JULY 9, 1056
I
IIb
INTERACTION OF DEUTERIUM WITH OLEFINS AND ALKANES ON CHROMIUM OXIDE GEL
Sir:
The background data for current interest in the mechanism of olefin hydrogenation are largely confined to platinum and nickel catalysts. I t seemed important to investigate as different a catalyst as possible. Chromium oxide gel1 was chosen because much is known about its behavior in other catalytic reactions. In reactions between hydro111 IV carbons and deuterium we find that i t yields prodRegardless of the details of the mechanism of this ucts which are isotopically much simpler than reaction, C.13 must become trigonal a t or near the those obtained with metallic catalysts. These transition state for the migration of (2.15 from (2.13 reactions are of both mechanistic and preparative to C.14. The two rings of the potential biphenyl interest. system then approach coaxiality. This sets up two ilftcr dehydration above 400°, the gel2 acquires diastereomeric transition state^,^ and the configura- hydrogenating activity a t low temperatures. Tation of the biphenyl becomes fixed when the react- ble I presents isotopic distribution patterns of proding system chooses to employ one of them in ther- ucts of experiments with 2 : l mixtures of deumodynamic preference to the other. For con- terium and hydrocarbon a t space rates of about 1 venience, we discuss the choice between the cc. of liquid hydrocarbon per cc. of catalyst per metastable intermediates I I a and IIb, although the hour. At 42', the hexane from I-hexene is largely ( 1 ) T h e support of this work b y a g r a n t from t h e National Science hexane-ds. Even a t - 7Fi0, similar hydrogenation Foundation is gratefully acknowledged. on nickel-kieselguhr gives broad distribution of ex( 2 ) J. M. Bijvoet, A. F. Peerdeman a n d A. J. v a n Bommel, .Vatwe, changed species3 168, 271 (1951). At - 20°, 1-butene yields butane-& nearly ex(3) We recognize t h a t because of t h e difference in symmetry orders between t h e asymmetric frames' (bisphenoid vs. regular tetrahedron), clusively. Cyclopentene behaves similarly at 27'. there is, in general, no conceptual way of relating a n axially asymmetric Mass spectrometric fragmentation patterns inconfiguration t o t h a t of a centrally asymmetric one. dicate that the butane is nearly all butane-1, (4) R. S. C a h n , C. K . Ingold a n d V. Prelog, Expcrientia, 12, 81 2-d2. The hexane prepared a t 42" is mainly 1,2-d2 (1956). ( 5 ) ( a ) K. W. Bentley a n d H. M. E. Cardwell, J. Chem. Soc., 3252 with smaller amounts of other dideuterohexanes, (1955); (b) J. Kalvoda, P. Buchsacher a n d 0. Jeger, Hela. Chim. Acta, principally 2,3-d4. 38, 1847 (1955). (6) (a) M. Freund, Ber., 33, 3234 (1905). (b) L. Small, L. J. Sargent a n d J. A. Bralley, J . O v p . Chenz , 12, 1839 (1947). (c) R. Robinson, .Yaliire, 160, 815 (1947). (d) K. R'. Bentley a n d R. Robinson, J . Chem. s o c . , 947 (1952). (7) Cf.J . .4.Berson and E. Brown, T H i s J O U R N A L , 1 7 , 450 (1983).
(1) W. A. Lazier a n d J. T'. Yaughen, THISJ O O R N A L , 64, 3080 (1932). (2) Prepared b y t h e urea method, R. L Burwell, J r . , ibid., 69, 160!1 (1Y3i) (3) C . D. Wagner, J. N. Wilson. J. 1%'. Otvtis a n d I>. P. Stevenson. J . Chrtn. P h y s . , 2 0 , 3 3 8 (1962).
