Synthesis of benzo[][1,5]diazocin-6(5)-one derivatives the Cu-catalysed oxidative cyclization of 2-aryl-1-indoles with 1,1-enediamines

• Published in: Chemical communications (Cambridge, England) Vol. 59; no. 9; pp. 1217 - 122
• Main Authors: Chen, Yi-Hua, Yang, Jing, Lu, Zi-Han, Zhao, Ke-Hua, Xie, Qi-Ying, Yan, Sheng-Jiao
• Format: Journal Article
• Published: 26.01.2023
• ISSN: 1359-7345; 1364-548X
• DOI: 10.1039/d2cc06388c

A novel protocol for the synthesis of highly functionalized benzo[ b ][1,5]diazocin-6(5 H )-one derivatives (BDCOs, 4 and 5 ) from 2-aryl-1 H -indoles and 1,1-enediamines was developed via a complex cascade of reactions including regioselective free radical oxidation, the 1,2-addition of imine, imine-enamine tautomerization, intramolecular cyclization, and ring expansion. The cascade reaction was enabled by refluxing a mixture of two substrates in the presence of di- tert -butyl peroxide (DTBP) as an oxidant and anhydrous CuI as a catalyst in toluene under argon protection. Consequently, a series of BDCOs ( 4 and 5 ) were synthesized with high regioselectivity in good yield. This protocol can be used for the synthesis of functionalized BDCOs via a one-pot oxidative annulation reaction rather than a multi-step reaction, which is suitable for both combinatorial and parallel syntheses of BDCOs. A novel protocol for the synthesis of highly functionalized benzo[ b ][1,5]diazocin-6(5 H )-one derivatives (BDCOs, 4 and 5 ) from 2-aryl-1 H -indoles and 1,1-enediamines was developed via a complex cascade of reactions.