Neurosteroid Analogues. 2. Total Synthesis and Electrophysiological Evaluation of Benz[e]indene Analogues of the Anesthetic Steroid Alphaxalone

Anesthetic steroid la and benz[e]indene 2 are known to have potent pharmacological actions at GABAa receptors. Anesthetic 11-ketosteroids such as alfaxalone (1b) are also known to have this activity. Evaluation of corresponding 5H-benz[e]inden-5-one analogs of 11-ketosteroids necessitated the development of an efficient route to these compounds. Accordingly, total synthesis of the 5H-benz[e]inden-5-ones 3 and 4 from the known 5H-inden-5-one precursor 5 is described. The structure of compound 3 has been verified by X-ray diffraction analysis. Electrophysiological evaluations of compounds 3 and 4 indicate that, unlike benz[e]indene 2, these compounds have weak pharmacological actions at GABAa receptors.