A process for the preparation of 1,2,3,4,8,9,10,10a-octahydro-7bH-cyclopenta[b][1,4]diazepino[6,7,1-hi]indole

A synthesis of 1,2,3,4,8,9,10,10a-octahydro-7bH-cyclopenta[b][1,4]diazepino[6,7,1-hi]indole is described exemplifying a new synthetic route to medicinally interesting compounds. The key step involves a cyclization of 2-(2,3,3a,8b-tetrahydrocyclopenta[b]indol-4(1H)-yl)-ethanamine with aqueous formaldehyde in the presence of trifluoroacetic acid. (C) 2004 Elsevier Ltd. All rights reserved.