Facile Chemodivergent Synthesis of Fused Indolo[2,3‑<i>b</i>]quinoxalines and Benzo[4,5]imidazo[1,2‑<i>c</i>]quinazolin-6(5<i>H</i>)‑ones: An Organocatalytic Trifluoromethanesulfonic Acid-Controlled Mechanistic Switch between Condensation and Ring Expansion of the Isatin Core.

ABSTRACT: A mild metal-free chemodivergent synthesis leading to products of two different chemotypes, such as indolo-[2,3-b]-quinoxalines and benzo-[4,5]-imidazo-[1,2-c]-quinazolin-6-(5H)-ones, has been described from common starting materials, isatin and 1,2-diaminobenzene, at room temperature in an environmentally benign EtOH solvent. The EtOH mediated condensation between isatin and 1,2-diaminobenzene delivers exclusively fused indolo-[2,3-b]-quinoxalines in good/excellent yields (65-89%) in 8 h, and catalytic protic acid (CF₃SO₃H) in EtOH furnishes N-fused benzo-[4,5]-imidazo-[1,2-c]-quinazolin-6-(5H)-ones selectively in good/excellent yields (66-88%) in 2 h via rearrangement of the isatin core following C2-C3 bond cleavage and N-at

SUBMITTER: Sheeba L 

PROVIDER: S-EPMC12756839 | biostudies-literature | 2025 Dec

REPOSITORIES: biostudies-literature