Synthetic studies towards 1,5-benzodiazocines

Anthranilonitrile reacted with phenylmagnesium bromide to yield a dianion, which when heated (∼120 °C) yielded the condensation product 2-(2-aminophenyl)-2,4-diphenyl-1,2-dihydroquinazoline 8. This heterocycle, when treated with palladium acetate, was converted into 6,12-diphenyldibenzo[b,f][1,5]diazocine 9. Methylmagnesium bromide and anthranilonitrile, under similar conditions directly gave a nitrogen-bridged diazocine, whose structure was determined by X-ray crystallography and also proven to be an analogue of Tröger’s base. Acid-induced condensation of 2-amino-3-methoxybenzaldehyde gave the trimeric product 45 rather than a dibenzo[b,f][1,5]diazocine.