7alpha-Carboalkoxy steroidal spirolactones as aldosterone antagonists

A variety of esters of 17-hydroxy-3-oxo-17alpha-pregn-4-ene-7alpha,21-dicarboxylic acid-gamma-lactone (7a) was synthetized in a sequence using the corresponding 3-oxo-4,6-diene (2) as starting material. The methyl (5), ethyl (7c), and isopropyl (7e) esters as well as the C-1 unsaturated methyl ester (8a) showed good oral and subcutaneous activity (MED less than or equal to 0.41 mg). Some general observations on structure-activity relationships are made.