M. Alajarín, A. Molina, P. Sánchez-Andrada
Jan 22, 1999
Citations
0
Influential Citations
21
Citations
Journal
Journal of Organic Chemistry
Abstract
Aza-Wittig reactions of bis(iminophosphorane) 1 derived from 2,2‘-diazidobiphenyl with aromatic isocyanates provided dibenzo[d,f]-1,3-diazetidino[1,2-a]diazepine derivatives 2 in moderate yields. Similar results can be achieved from the reaction of 2,2‘-bis(isothiocyanato)biphenyl 4 with aryliminophosphoranes. Treatment of bis(isothiocyanate) 4 with arylamines and further dehydrosulfurization of the resulting bis(thioureas) leads to the seven-membered ring guanidines 8. N-2-(2‘-Azido)biphenyl-N‘-arylcarbodiimides 13 react with 1 equiv of triphenylphosphane to give zwitterionic compounds 15, which undergo either hydrolytic cleavage to afford the guanidines 8 or react with 1 equiv of aromatic isocyanates to provide 2. Cross-experiments suggest that the conversion 15 → 2 takes place through a nonisolable bis(carbodiimide) that undergoes an intramolecular [2 + 2] cycloaddition at the final step. The reaction of bis(iminophosphorane) 1 with an excess of carbon dioxide leads to a mixture of the tricyclic 1,3-di...