16,17-ACETAL DERIVATIVES OF THE RETRO PREGNANE SERIES

摘要

The invention comprises compounds of formula FORM:1123561/C2/1 where R3 is a 3-keto-4-dehydro-, 3-keto-4,6-bisdehydro-, 3-keto-1,4,6-trisdehydro, 3-alkoxy-3,5 bisdehydro or 3-acyloxy-3,5-bisdehydro-group, and their preparation by (a) treatment of a 16a -hydroxy, etherified hydroxy or esterified hydroxy group with a base or a dehydrating agent, (b) enol etherification or acylation, or (c) 1, 2 and/or 6, 7 dehydrogenation. The compounds of the invention have gonadotrophin-inhibiting and weak progestational activity and may be used in pharmaceutical compositions in combination with a carrier. Reference has been directed by the Comptroller to Specification 929,271.