Synthesis of Non-Steroidal Estrogen Agonists for Hormone Replacement Therapy and Synthesis and Reactivity of 2,3-Substituted 5-Silyl-7-Oxa-Bicyclo[2.2.1]Heptenes and Heptadienes

The focus of the research described in this section of the thesis is the synthesis of compounds expected to bind strongly to both the estrogen β and α receptors and act as estrogen agonists. Based on earlier results in our group and docking studies we prepared a series of A-CD analogs, compounds 1, in which the usual 13-methyl group was replaced by an ethyl group. Docking studies also indicated that substituents at C8 could lead to enhancement of binding to the estrogen receptor. With this in mind two such derivatives, compounds 2 were prepared. A major concern in the use of estradiol in hormone replacement therapy is its potential metabolism of dangerous ortho-quinones. The 1,2-naphthalenediol derivatives 3 avoid this possibility. They were predicted to be potent binders to the estrogen receptors with the naphthalene diol portion serving as rings A and B and the hydroxyl group taking the place of the 17-OH group of estradiol. The preparation of several derivatives of 2 is reported. The estrogen receptor binding [ERB] relative to estradiol as standard has been determined at the University of Illinois for a number of the compounds prepared in this thesis. Unfortunately, the results were not as encouraging as expected. Importantly, all of the 13-ethyl derivatives tested showed lower binding affinity compared to the 13-methyl analogs. Similarly, the derivatives with substituents at C8 do not show higher activity than those having only hydrogens at C8. Finally, the situation with the naphthalene derivatives is, at this stage, still not completely resolved. The binding for the compounds thus tested is quite low, but it must be admitted that the structures thus far synthesized have a much lower LogP than estradiol, a factor known to greatly decrease the binding constants to the estrogen receptors