The syntheses of 2,19-(methyleneoxy)androst-4-ene-3,17-dione (4a), a potent, time-dependent inhibitor of human placental aromatase, and its thio (4b), amino (5), and methylene (14) analogs are described. The key step in the construction of 4a, 4b, and 5 is a Lewis acid-mediated intramolecular alkylation of an A-ring O-trimethylsilyl dienol ether.
The syntheses of 2,19-(methyleneoxy)androst-4-ene-3,17-dione (4a), a potent, time-dependent inhibitor of human placental aromatase, and its thio (4b), amino (5), and methylene (14) analogs are described. The key step in the construction of 4a, 4b, and 5 is a Lewis acid-mediated intramolecular alkylation of an A-ring O-trimethylsilyl dienol ether.