Ritter Reactions. IX. Transannular Addition of Nitriles to the 5H-Dibenzo[a,d]cycloheptene Ring System

Abstract

The 5H-dibenzo[a,d]cyclohepten-5-ols (1a-e) undergo sequential intramolecular and conventional Ritter reactions with acetonitrile to afford the {5,10-(nitrilometheno)-5H-dibenzo[a,d]cyclohepten-11-yl}acetamides (6a-e). Typical yields for these one-flask conversions are 52-64%, except for the reaction of (1a) where production of the dimeric substance (4a) is favoured. Alcohol (1a) can provide either type of product in good yield, depending on the conditions employed, when reacted with benzonitrile. The molecular skeleton present in the adducts (6) has been confirmed by determination of the crystal structure of (6c) [C₂₅H₂₂N₂O, Pī, a 9.188(3), b 14.632(5), c 16.563(9) Ǻ, α 115.64(2), β 90.92(2), γ 96.29(2)°, Z 4, R 0.043].