The aza-annulation of enamino ester substrates has been demonstrated as an efficient alternative to the syntheses of non-benzodiazepine sleep inducers. Enamino ester substrates derived from aryl, thiophene, and indole functionality were prepared from the corresponding ethyl amines by isothiocyanate formation followed by acid catalyzed cyclization. (C) 1997 Elsevier Science Ltd.