Substrate Switchable Pathway for Selective Construction of Bridged Dibenzo[b,f][1,5]diazocines and Bridged Spiromethanodibenzo[,]azepines.

An operationally simple method for the synthesis of bridged dibenzo[b,f][1,5]diazocines and bridged spiromethanodibenzo[,]azepines exhibiting bridged eight-membered and seven-membered molecular architecture is reported. This unique approach is based on substrate selective mechanistic pathway, including an unprecendented aerial oxidation-driven mechanism for the synthesis of bridged spiromethanodibenzo[,]azepines. The reaction is highly atom economic, and in addition, it allows the construction of two rings and four bonds in a single operation under metal-free condition. The easy availability of β enaminone and ortho phathalaldehyde as starting materials and the simple operation make this approach suitable for the preparation of important dibenzo[b,f][1,5]diazocine and spiromethanodibenzo[,]azepine cores.