STRUCTURE AND CONFORMATION OF SOME SULFONE DERIVATIVES. Y.S. Chen, S. Narasinga Rao, Elizabeth J. Holt*, K.V. Narayana Raju and M. Krishnaiah⁺, Department of Physics, University of Central Oklahoma, Edmond, Oklahoma, Dept. of Chemistry, Oklahoma State University, Stillwater, Oklahoma*, Dept. of Physics, Sri Venkateswara University, Tirupati, India⁺.

Sulfones are antibacterial and antifungal agents. The antifungal activity of some unsaturated sulfones has been found to be dependent upon substituent and stereochemical effects. (E)-3-[2(phenylsulfonyl) ethenyl]-4H-l-benzopyran-4-one has been observed to display antifungal activity against currularia lunate and furasium oxysparum (Mukundam, 1990). In the interest of exploiting and increasing this activity, we have synthesized a series of compounds which are derived from these active antifungal agents but with substituents at the 6 position of the 4H-1-benzopyran-4- one ring and with variation of the parasubstituent on the phenyl ring: (I) none (II) para-chloro (III) para-chloro, 6-chloro (IV) para-bromo, 6 bromo and (V) para-chloro, 6-methoxy. Our aim is to observe the influences of these changes upon the conformation of the ethenylsulfone moiety.

The solid state structures of molecules confirm the transconformation at C7-C8 for I & II, and C9-C10 at III, IV and V. Bond distances reflect electron delocalization in the 04-C10-C9- C8C7 (I), 03-C6-C5-C8-C7 (II) and 01-C2-C3-C9-C10. (III, IV and V), chains. There are no significant differences in details of angles and distances for all five structures. All molecules show coplanarity of the sulfur, ethene and chromanone ring moities. However, in the methoxy substituted chromanone derivative (V), 03 lies on that plane (d=0.05) whereas in III & IV, 03 is respectively 0.569 and 0.548 Å from that plane. Thus the Sll, 01, 03, C2-C10 plane bisects the C12-S11-04 angle in (III) as seen in a projection down the S11-C10 bond, but is perpendicular to the S11-C12 bond in the same projection for IV & V.

Mukundam, (1990), Ph.D. Thesis, Sri Venkateswara University, Tirupati, India.