CRYSTAL-STRUCTURE OF THE PRODUCT OF A CONDENSATION REACTION OF (+ -)-GOSSYPOL WITH (R)-(+)-1-PHENYLETHYLAMINE - WHY DO DIASTEREOISOMERIC DIAMINOGOSSYPOLS COCRYSTALLIZE/

The crystal structure of a compound obtained in a condensation reactio n of (+/-)-gossypol with (R)-(+)-phenylethylamine has been determined by X-ray structure analysis. The crystals of C46H48O6N2 . (C4H8O2)2 ar e monoclinic, space group P2(1), a = 21.243(3), b = 8.666(1), c = 28.6 51(4) angstrom, beta = 108.24(1)-degree, V = 5009(3) angstrom3, Z = 4, D(x) = 1.195 g cm-3, mu(Cu K(alpha))=0.66 mm-1, T = 292 K. The struct ure has been solved by direct methods and refined to the final R value of 0.091 for 4290 observed reflections and 1049 parameters. There are two diastereoisomeric molecules of the host and four solvent molecule s in the asymmetric unit. The host molecules are H-bonded into chains with diastereoisomeric molecules alternating along the chain. The fact that the host prefers the association mode in which molecules with a different configuration of the 2,2'-binaphthyl moiety are H-bonded exp lains why separation of diastereoisomeric diaminogossypols by fraction al crystallization has been unsuccessful. The 1,4-dioxane molecules ar e accommodated in infinite channels but only every second guest molecu le in a channel is H-bonded to the host.