etherification uses toxic or hardly degradable alkylating agents. An eco-friendly tandem etherification/aromatization is presented to prepare estrone 3-secondary ethers from easily available dienone 1. Three marketed 3-etherified estrogen drugs were synthesized with the method from commercial available starting material.
after exploring a variety of C-19 substituents. 1,2-Dehydrogenation in combination with subsequent A-ring aromatization via retro-aldol reaction provided a flexible and efficient protocol for the synthesis of estrogens. To demonstrate the utility of the protocol, pharmaceutically attractive estrogens were synthesized from easily available 19-hydroxy-4-ene-3-keto steroids.