Steroids, L. Ring D Cleavage of D‐Trisubstituted Steroids

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Abstract
In alkaline medium, 17β‐hydroxy‐15‐(hydroxymethylene)androst‐5‐en‐16‐one (2a) is cleaved in two ways to give D‐seco compounds. Dilute bases in protic solvents cause 1,3‐dicarbonyl splitting to the 15‐formyl‐15,16‐seco‐16‐oic acid 3, while the use of sodium methanolate in benzene solution gives rise to 16,17‐splitting to afford the 15‐formyl‐16,17‐seco‐16,17‐dioic acid 5. Both seco compounds readily undergo lactolone ring closure to give 4a and 6a, respectively. The malonaldehyde moiety of 5 is transformed in two directions: either loss of the formyl group to give 3β‐hydroxy‐16,17‐secoandrost‐5‐ene‐16,17‐dioic acid (7a) or decarboxylation to 3β‐hydroxy‐16‐oxo‐16,17‐secoandrost‐5‐en‐17‐oic acid (9) is observed.