Brønsted acidic ionic liquid-promoted direct C3-acylation of N-unsubstituted indoles with acid anhydrides under microwave irradiation

Abstract

A green and efficient method for the synthesis of 3-acylindoles using a Brønsted acidic ionic liquid under microwave irradiation has been developed.

Ketone-Directed Cobalt(III)-Catalyzed Regioselective C2 Amidation of Indoles

“…1 H NMR (500 MHz, CDCl 3 ): δ 9.17 (s, 1H), 8.42–8.40 (m, 1H), 7.88 (d, J = 2.0 Hz, 1H), 7.43–7.27 (m, 3H), 2.86 (t, J = 7.5 Hz, 2H), 1.86–1.79 (m, 2H), 1.02 (t, J = 7.0 Hz, 3H). These data were similar to those reported in the literature …”

Synthesis of benzo[4,5]imidazo[1,2-a]pyrimidines and 2,3-dihydroquinazolin-4(1H)-ones under metal-free and solvent-free conditions for minimizing waste generation

“…Initially, [(4-SO 3 H)BMIM]HSO 4 ionic liquid was prepared as reported in the literature. 22 The structure of [(4-SO 3 H)BMIM]HSO 4 was confirmed by NMR, FT-IR, TGA, and HR-MS (ESI, Section S2 † ). The as-synthesized [(4-SO 3 H)BMIM]HSO 4 was obtained in high yield after a simple purification step.…”

“…[(4-SO 3 H)BMIM]HSO 4 was synthesized via a one-pot two-step procedure under solvent-free sonication according to our previous literature report. 22 …”

Reusable Brønsted Acidic Ionic Liquid Efficiently Catalyzed N-Formylation and N-Acylation of Amines

“…The method was step efficient and featured a wide substrate scope, while the use of HPA (H 3 PW 12 O 40 , H 3 PMo 12 O 40 ) caused environmental problems and high cost as well (Scheme d). Brønsted acidic ionic liquids (BAILs), first reported by Cole et al in 2002, have gained considerable attention because of their high thermal stability, high acidity, simple separation, nontoxicity, and inertness toward air and water. − Indeed, to date, BAILs as catalysts have gained widespread applications in a wide range of organic transformations, such as esterification, − alkylation, − acetalization, , heterocyclic synthesis, − and so on. , As an ongoing effort in developing new synthetic methodology using metal-free BAILs as catalysts in N -formylation and N -acylation, we report our recent progress in the preparation of metal-free BAILs and their applications in solvent-free amidation reactions (Figure ).…”

“…44−47 Indeed, to date, BAILs as catalysts have gained widespread applications in a wide range of organic transformations, such as esterification, 48−50 alkylation, 51−53 acetalization, 54,55 heterocyclic synthesis, 56−58 and so on. 59,60 As an ongoing effort in developing new synthetic methodology using metal-free BAILs as catalysts in N-formylation and N-acylation, we report our recent progress in the preparation of metal-free BAILs and their applications in solvent-free amidation reactions (Figure 1).…”