Aldosterone antagonists. 2. New 7 alpha-(acetylthio)-15,16-methylene spirolactones

Some 15,16-methylene derivatives of the aldosterone antagonist spironolactone were synthesized with the purpose of increasing the antialdosterone potency and reducing the endocrinological effects of this standard compound. By introduction of a 1,2-double bond and a 15 beta,16 beta-methylene ring in the spironolactone molecule both goals were achieved. In animal studies mespirenone exhibited a threefold-greater antialdosterone potency and less than 10% of the antiandrogenic activity of spironolactone.