Estrone, one of the major mammalian estrogens, is an aromatized C18 steroid with a 3-hydroxyl group and a 17-ketone. It is produced in vivo from androstenedione or from testosterone via estradiol. It is produced primarily in the ovaries, placenta, and in peripheral tissues (especially adipose tissue) through conversion of adrostenedione. Estrone may be further metabolized to 16-alpha-hydroxyestrone, which may be reduced to estriol by estradiol dehydrogenase. Estrogens enter the cells of responsive tissues (e.g. female organs, breasts, hypothalamus, pituitary) where they interact with estrogen receptors. Hormone-bound estrogen receptors dimerize, translocate to the nucleus of cells and bind to estrogen response elements (ERE) of genes. Binding to ERE alters the transcription rate of affected genes. Estrogens increase the hepatic synthesis of sex hormone binding globulin (SHBG), thyroid-binding globulin (TBG), and other serum proteins and suppress follicle-stimulating hormone (FSH) release from the anterior pituitary. Estrone dl-Form is a derivative of estrone. As early as 1935 extensive research programs directed toward the total synthesis of the female sex hormone estrone were well under way. These studies have since been continued with increasing interest in laboratories all over the world. In 1942 Bachmann, Kushner and Stevenson succeeded in synthesizing a stereoisomer of the hormone,''estrone a." Using essentially the same synthetic scheme as Bachmann, et al., Anner and Miescher were able to isolate additional stereoisomers including dl-estrone (Estrone, (+-)-Isomer) . Six of the eight possible racemic forms, estrone, a-f, have now been reported. Dl-Estrone (Estrone, (+-)-Isomer) is less active than Estrone.