[6 + 3–] Cycloadditions of 1,1- and 1,3-diphenyl-2-aza-allyl-lithium to cycloheptatriene

Abstract

Reactions between cycloheptatriene and 1,1-diphenyl-(1) and 1,3-diphenyl-2-aza-allyl-lithium gave [6 + 3^–] cycloadducts exclusively. The products were identified as 7,7-diphenyl-8-azabicyclo[4.3.1]deca-2,4-diene (2), and trans-(5) and cis-7,9-diphenyl-8-azabicyclo[4.3.1]deca-2,4-diene (6). [6 + 3^–] Cycloadditions, the anionic analogues of [6 + 4] cycloreactions, have not been reported previously. Evidence is presented which is consistent with a concerted mechanism for these reactions.