Copper catalyzed aerobic oxidative cyclization and ketonization: one pot synthesis of benzoimidazo[1,2-a]imidazolones.
A highly efficient synthesis of benzoimidazo[1,2-a]imidazolone through a novel oxidative 5-exo-dig cyclization-ketonization cascade of 2-aminobenzimidazole, aldehyde and terminal alkyne has been explored under aerobic conditions. The reaction proceeds through copper-catalyzed addition of terminal alkynes to imines derived from 2-aminobenzimidazole with aldehyde followed by intramolecular cyclization. The atmospheric molecular oxygen acts as an oxygen source for the newly formed carbonyl group in the final product.
Department of Applied Chemistry, National Chiao-Tung University, 1001, Ta-Hseuh Road, Hsinchu 300-10, Taiwan, Republic of China. cmsun@mail.nctu.edu.tw.
Manikandan
M
Selvaraju
Department of Applied Chemistry, National Chiao-Tung University, 1001, Ta-Hseuh Road, Hsinchu 300-10, Taiwan, Republic of China. cmsun@mail.nctu.edu.tw.
Tzuen-Yang
TY
Ye
Department of Applied Chemistry, National Chiao-Tung University, 1001, Ta-Hseuh Road, Hsinchu 300-10, Taiwan, Republic of China. cmsun@mail.nctu.edu.tw and Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, 100, Shih-Chuan 1st Road, Kaohsiung 807-08, Taiwan, Republic of China.
Chia-Hsin
CH
Li
Department of Applied Chemistry, National Chiao-Tung University, 1001, Ta-Hseuh Road, Hsinchu 300-10, Taiwan, Republic of China. cmsun@mail.nctu.edu.tw.
Pei-Heng
PH
Ho
Department of Applied Chemistry, National Chiao-Tung University, 1001, Ta-Hseuh Road, Hsinchu 300-10, Taiwan, Republic of China. cmsun@mail.nctu.edu.tw and Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, 100, Shih-Chuan 1st Road, Kaohsiung 807-08, Taiwan, Republic of China.
Chung-Ming
CM
Sun