Chemodivergent (4 + 3) cycloadditions of 2-indolylmethanols with 1,3,5-triazinanes: access to polycyclic indoles

Abstract

Reported herein are the chemodivergent (4 + 3) cycloadditions of 2-indolylmethanols with 1,3,5-triazinanes. As opposed to the previous (3 + n) cycloadditions of 2-indolylmethanols as three-atom synthons, this divergent protocol employs 2-indolylmethanols as platform four-atom synthons by using the OH group as a nucleophilic group. The gem-diaryl effect enables divergent regioselectivity. Primary 2-indolylmethanols display N1-nuleophilicity, while tertiary diaryl 2-indolylmethanols exhibit C3-nucleophilicity. As such, various polycyclic indoles, oxadiazepino[5,6-a]indoles and oxazepino[6,5-b]indoles, have been collectively prepared in good yields.