This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Zacharias, D. E. Articles by Fu, P. P. Search for Related Content PubMed PubMed Citation Articles by Zacharias, D. E. Articles by Fu, P. P.

Molecular Structure of the K-Region cis-Dihydrodiol of 7,12-Dimethylbenz[a]anthracene¹

The Institute for Cancer Research, The Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111 [D. E. Z., J. P. G.], and Ben May Laboratory for Cancer Research, The University of Chicago, Chicago, Illinois 60637 [R. G. H., P. P. F.]

The molecular structure and conformation of the cis-5,6-dihydrodiol of 7,12-dimethylbenz[a]anthracene has been determined by an X-ray crystallographic analysis. The compound crystallizes in the space group P2₁/a with cell dimensions a = 17.799(6), b = 33.211(8), c = 5.241(1) Å, ß = 91.88(2)°. There are two molecules, designated A and B in the asymmetrical unit, that are not related to each other by crystallographic symmetry. Their conformations are almost identical, and there are no significant differences in their bond lengths or angles. In both molecules the 5-hydroxyl group is equatorial while the 6-hydroxyl group is axial. This conformation is probably forced by steric hindrance between the hydroxyl group, O–6, and the hydrogen atoms of the 7-methyl group. The molecules pack in the crystal by forming hydrogen bonds between the hydroxyl groups of adjacent molecules, A with A, B with B, and A with B. The ring system of the cis-5,6-dihydrodiol is much more buckled than is that in 7,12-dimethylbenz[a]anthracene itself. The angle between the two outermost rings is 36°, the deviation from planarity being primarily a consequence of the partial saturation in the ring containing the two hydroxyl groups. Extrapolation of these results to other dihydrodiol derivatives of carcinogenic hydrocarbons permits some predictions of preferred molecular geometry. Thus, the 8,9-dihydrodiol-10,11-epoxide of 7,12-dimethylbenz[a]anthracene, analogous to the biologically active 7,8-dihydrodiol-9,10-epoxide of benzo[a]pyrene, a mutagen that is believed to be an active intermediate in carcinogenesis by benzo[a]pyrene, should probably exist preferentially in a conformation bearing the 8-hydroxyl group in the axial orientation.

¹ This research was supported by USPHS Grants CA-10925, CA-06927, CA-11968, and RR-05539 from the NIH; BC-132 from the American Cancer Society; AG-370 from the National Science Foundation; and by an appropriation from the Commonwealth of Pennsylvania.

Received 10/28/76. Accepted 11/23/76.

This article has been cited by other articles:

				J. D. Moody, P. P. Fu, J. P. Freeman, and C. E. Cerniglia Regio- and Stereoselective Metabolism of 7,12-Dimethylbenz[a]anthracene by Mycobacterium vanbaalenii PYR-1 Appl. Envir. Microbiol., July 1, 2003; 69(7): 3924 - 3931. [Abstract] [Full Text] [PDF]