ORGN 136

In collaboration with a recent medicinal chemistry program, it became necessary to develop a practical synthesis of diazepinoindolines 1.  This new synthesis is exemplified by the preparation of one of the simplest structures within this series, 1, 2, 3, 4, 8, 9, 10, 10a-octahydro-7bH-cyclopenta[b][1,4]diazepino[6, 7, 1- hi]indole (2).  The key step involves a cyclization of 2-(2, 3, 3a, 8b-tetrahydrocyclopenta[b]indol-4(1H)-yl)ethanamine (3) with aqueous formaldehyde in the presence of trifluoroacetic acid.