Unusual formation of sterically hindered primary amines in a series of pyrrolo- and pyrido[1,2-a]indoles

Abstract

2,3-Dihydro-2,2,9-trimethyl-1H-pyrrolo[1,2-a]indol-1-amine and its 1-(1-pyrrolidinyl) analog have been synthesized from the corresponding 1-ol via mesylation in pyridine followed by treatment with pyrrolidine. Mechanisms of the former, unexpected amination are briefly discussed. Evidence is presented that the pyridine ring serves as a masked amino group. The phenomenon is partly attributed to steric congestion. Similar preparation of 2-bromo-6,7,8,9-tetrahydro-8,8,10-trimethylpyridol[1,2-a]indol-9-amine supports this notion.