Stereoselective Routes to Hexahydropyrroloindoles and Tetrahydropyrroloquinolines from Activated Aziridines and Electron Deficient 3 H -Indoles.

An unprecedented and novel synthetic route to hexahydropyrrolo[2,3- b ]indoles bearing cis -contiguous stereocenters with excellent stereoselectivities (ee of >99%, dr of ≤99:1) has been disclosed that proceeds through the ring opening of activated aziridines with electron deficient 4-substituted indoles followed by a novel cyclization in a domino fashion, thereby obviating the use of 3-substituted indoles as the prerequisite nucleophile. Another efficient synthetic route to tetrahydropyrrolo[4,3,2- de ]quinolines in excellent yields (≤93%) and excellent enantioselectivity (ee of >99%) has been established via ring opening of activated aziridines with 4-bromo-1-methyl-1 H -indole at relatively higher temperatures followed by Cu(I)-catalyzed intramolecular C-N cyclization in the same pot. The stability and the formation of products at different temperatures are explained by computational studies.