Substituted benzopyrans as selective estrogen receptor-beta agonists

#The present invention relates to novel cycloalkyl-benzopyrans and derivatives thereof, compositions containing those compounds, their use as selective estrogen receptor-beta agonists, and their use in the treatment of estrogen receptor-beta mediated diseases such as prostate cancer, benign prostatic hyperplasia (hypertrophy), testicular cancer, ovarian cancer, lung cancer, cardiovascular diseases, neurodegenerative disorders, urinary incontinence, central nervous system (CNS) disorders, gastrointestinal (GI) tract disorders, and osteoporosis.

#Estrogens play important roles in the development and homeostasis of the reproductive, central nervous, skeletal, and cardiovascular systems of both males and females. Recently, a new ER isoform, ER-beta (also known as ER-beta1) was cloned from a rat prostatic cDNA library and is present in murine and human prostates. Consequently, the previous ER is now designated as ER-alpha. ER-alpha and ER-beta share high amino acid homology, have similar 17-β Estradiol (E2) binding affinities, and can hetero- or homodimerize to form a signaling complex; Kuiper G G, et al., Endocrinol. 138: 863-70 (1997); Kuiper G G et al., Proc. Natl. Acad. Sci. USA 93: 5925-30 (1996). Although E2 activates both ER-alpha and ER-beta, ER-alpha stimulates transcription and cellular proliferation, while ER-beta suppresses ER-alpha activation. Interestingly, 3-beta, 17-beta-androstanediol and 5-alpha-androstane have been proposed to be endogenous ligands for ER-beta; Weihua Z. et al. PNAS 98: 6330-5 (2001). 3-Beta, 17-beta-androstanediol is a major metabolite of dihydrotestosterone (DHT), the 5-alpha-reduced active intracellular androgen in male accessory sex organs. ER-beta activation also stimulates increased glutathione S-transferase and quinone reductase expression. These two enzymes have been shown to possess chemoprotective detoxification properties; Chang W Y et al., Prostate 40: 115-24 (1999); Montano MM et al., J. Biol. Chem. 273: 25443-9 (1998).

#With the recent identification of ER-beta, and the recognition that ER-alpha and ER-beta have different biological roles, ER-selective modulators would similarly possess significant clinical utility. Since ER-beta is strongly expressed in a number of tissues including prostate, bladder, ovary, testis, lung, small intestine, vascular endothelium, and various parts of the brain, compounds that selectively modulate ER-beta would be of clinical importance in the treatment of a variety of disease conditions, such as prostate cancer, testicular cancer, ovarian cancer, lung cancer, cardiovascular diseases, neurodegenerative disorders, urinary incontinence, CNS disorders, GI tract disorders, and osteoporosis. Such compounds would have minimal effect on tissues that contain ER-alpha, and thus exhibit different side-effect profiles. Thus, ER-beta agonists will display different therapeutic profiles compared to ER-alpha antagonists or agonists, and would be preferentially beneficial in tissues relying on ER-beta signaling.

#As used in this application:

#a) the term “C1-C6 alkyl” refers to a branched or straight chained alkyl radical containing from 1 to 6 carbon atoms, such as methyl (Me), ethyl (Et), n-propyl, isopropyl, n-butyl, isobutyl, sec butyl (s-Bu), tert-butyl (t-Bu), pentyl, hexyl, etc.;

#b) the term “C2-C4 alkenyl” refers to a straight or branched