Synthesis of 3-substituted cyclopenta[b]indoles

When reacting with I-2, 2-(cyclopent-2-enyl)anilines undergo cyclization into 3-iodo-1,2,3,3a,4,8b-hexahydrocyclopenta[b]indoles in high yields. The minor reaction products were 3,5- or 3,7-diiodoindolines. Ammonolysis of 3-iodo-5-methyl-1,2,3,3a,4,8b-hexahydrocyclopenta[b]indole or its N-chloroacetyl derivative results in 3-amino-5-methyl-1,2,3,3a,4,8b-hexahydro- and 5-methyl-1,3a,4,8b-tetrahydrocyclopenta[b]indoles.