Metal‐Free Ring Opening Cyclization of Cyclopropane Carbaldehydes and N‐Benzyl Anilines: An Eco‐Friendly Access to Functionalized Benzo[b]azepine Derivatives

Abstract Herein, we report a p ‐toluenesulfonic acid (PTSA) initiated mild and user‐friendly ring opening/domino ring opening cyclization reaction (depends on substituent present in N ‐benzyl aniline) of cyclopropane carbaldehyde and N ‐benzyl aniline towards the formation of substituted 4‐amino butanal/2,3‐dihydro‐1 H ‐benzo[ b ]azepine. The product dihydro‐1 H ‐benzo[ b ]azepine was also converted into the corresponding tetrahydro‐1 H ‐benzo[ b ]azepine. magnified image