title: Microwave Controlled Reductive Cyclization: A Selective Synthesis of Novel Benzimidazole-alkyloxypyrrolo[1,2-a]quinoxalinones.
abstract: An efficient cascade synthesis of novel benzimidazole linked alkyloxypyrrolo[1,2-a]quinoxalinones was explored on soluble polymer support under microwave irradiation. Two exclusive protocols have been developed for the partial and full reductive cyclization by controlling the microwave energy. Commencing from the same substrate, ortho nitro pyrrol carboxylates, N-hydroxy pyrroloquinoxalinones were obtained by partial reductive cyclization (60 °C, 7 min), and the synthesis of pyrroloquinoxalinones was accomplished by full reductive cyclization (85 °C, 12 min). This method represents the first synthesis of N-hydroxy pyrroloquinoxalinones using Pd/C and ammonium formate as reducing agents. Further employing a variety of alkyl bromides, the obtained pyrroloquinoxalinones were transformed to their corresponding O- and N-alkylated analogues to deliver the diversified, novel molecular entities.
authors.affiliation: †Department of Applied Chemistry, National Chiao Tung University, 1001 Ta-Hseuh Road, Hsinchu 300-10, Taiwan.
authors.forename: Sandip
authors.initials: S
authors.lastname: Dhole
authors.affiliation: †Department of Applied Chemistry, National Chiao Tung University, 1001 Ta-Hseuh Road, Hsinchu 300-10, Taiwan.
authors.forename: Manikandan
authors.initials: M
authors.lastname: Selvaraju
authors.affiliation: †Department of Applied Chemistry, National Chiao Tung University, 1001 Ta-Hseuh Road, Hsinchu 300-10, Taiwan.
authors.forename: Barnali
authors.initials: B
authors.lastname: Maiti
authors.affiliation: †Department of Applied Chemistry, National Chiao Tung University, 1001 Ta-Hseuh Road, Hsinchu 300-10, Taiwan.
authors.forename: Kaushik
authors.initials: K
authors.lastname: Chanda
authors.affiliation: †Department of Applied Chemistry, National Chiao Tung University, 1001 Ta-Hseuh Road, Hsinchu 300-10, Taiwan.|‡Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, 100, Shih-Chuan first Road, Kaohsiung 807-08, Taiwan.
authors.forename: Chung-Ming
authors.initials: CM
authors.lastname: Sun
mesh_terms: D001562:Benzimidazoles / Q000138:chemical synthesis* / Q000737:chemistry; D018360:Crystallography, X-Ray; D003500:Cyclization; D008872:Microwaves; D008958:Models, Molecular; D015394:Molecular Structure; D011758:Pyrroles / Q000138:chemical synthesis* / Q000737:chemistry*; D011810:Quinoxalines / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D001562:Benzimidazoles; D011758:Pyrroles; D011810:Quinoxalines
keywords: microwave-assisted; polymer supported; pyrroloquinoxalinones; reductive cyclization