Novel 6-substituted oxa- or azasteroid compound

摘要

6-Substituted oxa- or azasteroid compounds represented by the formula have an excellent aromatase inhibition action, and are useful for prophylaxis or treatment of diseases caused by estrogens such as, for example, breast cancer, uterine cancer and prostatic hypertrophy. The characteristics of such a compound is that an oxygen or nitrogen atom is introduced in the D ring portion, and the 6-position of the steroid skeleton (substituent R<1>) is substituted with -S-R<2> wherein R<2> represents a hydrogen atom, a lower alkyl group, a cyano group or an acyl group; -O-R<3> wherein R<3> represents a hydrogen atom, a lower alkyl group or an acyl group; an azido group or an amino group.