4′-Substituted bicyclic pyridones were prepared and evaluated as non-steroidal inhibitors of type 1 and 2 steroid 5α-reductase (SR). A range of 4′-substituents were incorporated into the bicyclic scaffold to investigate SAR within and across different classes of non- steroidal inhibitors of SR. Bicyclic pyridones containing a 4′-benzoyl or long carbon chain tether showed more potent inhibition against type 1 SR than inhibitors with N-substituted ...