116506-54-8Relevant articles and documents
Synthesis of the equine estrogen metabolites 2-hydroxyequilin and 2- hydroxyequilenin
Zhang, Fagen,Bolton, Judy L.
, p. 200 - 203 (2007/10/03)
Equilin and equilenin make up approximately 20% of Premarin which is currently the most popular estrogen replacement therapy. Although there are numerous health benefits of estrogen replacement therapy, there are concerns over the link between estrogen replacement therapy and breast and endometrial cancer risk. One potential mechanism of estrogen carcinogenesis involves metabolism of estrogens to 2- and 4-hydroxylated catechols which are further oxidized to electrophilic/redox active o-quinones which have the potential to both initiate and promote the carcinogenic process. In this investigation, we have synthesized potential metabolites of equilin and equilenin, 2- hydroxyequilin and 2-hydroxyequilenin, respectively, as well as their methyl ether metabolites. These compounds were synthesized from commercially available optically pure equilin via a practical and efficient approach; five steps gave 2-methoxyequilin from which 2-hydroxyequilin was prepared by BBr3-catalyzed demethylation in one step. Similarly, treating 2- methoxyequilin with SeO2 followed by demethylation with BBr3 produced 2- hydroxyequilenin. The structures of the catechols as well as those of their methoxy ethers were unambiguously characterized by one-dimensional and two- dimensional NMR experiments, including 1H, 13C, APT, COSY, HMBC, and HMQC as well as mass spectrometry.
SYNTHESIS OF 2-METHOXY AND 4-METHOXY EQUINE ESTROGENS
Pemmaraju, N. Rao,Somawardhana, Chandrasiri W.
, p. 419 - 432 (2007/10/02)
4-Methoxyequilin and 2-methoxyequilin were synthesized from the corresponding 4-bromoequilin and 2-iodoequilin derivatives, respectively, by nucleophilic displacement of halogen with methoxide ion in the presence of copper(II)chloride and 15-crown-5-ether. 4-Bromoequilin was prepared by reacting equilin with one equivalent of N-bromoacetamide. 2-Iodoequilin was prepared by reductive dehalogenation of 2,4-diiodoequilin, which in turn was obtained by treatment of equilin with two equivalents of iodine in methanolic ammonium hydroxide solution. 4-Methoxyequilenin and 2-methoxyequilenin were prepared from the corresponding 4-iodo- and 2-iodo-7ξ,8ξ-epoxyestrone derivatives, respectively.Nucleophilic displacement of iodine with methoxide ion was carried out as described earlier with simultaneous aromatization of the B ring leading to 4- and 2-methoxyequilenin derivatives.Alternatively, 4-methoxyequilenin was obtained from 4-methoxyequilin by selenium dioxide oxidation.
