Ring-substituted 1,2-dialkylated 1,2-bis(hydroxyphenyl)ethanes. 1. Synthesis and estrogen receptor binding affinity of 2,2'- and 3,3'-disubstituted hexestrols.

The syntheses of symmetrically 3,3'- and 2,2'-disubstituted meso hexestrol derivatives are described [3,3'-substituents: OH (1), F (2), Cl (3), Br (4), I (5), CH2N(CH3)2 (6), CH3 (7), CH2OCH3 (8), CH2OC2H5 (9), CH2OH (10), NO2 (11), NH2 (12), N(CH3)2 (13), COCH3 (14), and C2H5 (15); 2,2'-substituents: OH (16), F (17), Cl (18), Br (19), CH3 (20), and C2H5 (21)]. The synthesis of 1-3 was accomplished by reductive coupling of the propiophenones with TiCl4/Zn and subsequent hydrogenation of the cis-3,4-diphenylhex-3-enes. Compounds 4-15 were obtained by substitution of hexestrol, while compounds 16-21 were synthesized by coupling the 1-phenyl-1-propanols with TiCl3/LiAlH4 and separation of the meso diastereomers. The binding affinity of these compounds to the calf uterine estrogen receptor was measured relative to that of [3H]estradiol by a competitive binding assay. All test compounds showed relative binding affinity (RBA) values between 32 and less than 0.01% that of estradiol. Only meso-3,4-bis(2,4-dihydroxyphenyl)hexane (16) showed an estrogen receptor binding affinity comparable to that of hexestrol (32 and 27%, respectively). Compounds exhibiting RBA values of greater than 5% were evaluated in the mouse uterine weight test. All of them showed uterotrophic activity. Compounds 2, 7, 16, 17, and 20 were strongly active in very small doses (1 microgram per animal per day), while 1 and 12 produced full uterotrophic effects only in high doses and inhibited the estrone-stimulated uterine growth strongly in small doses (59 and 78% inhibition, respectively).