title: Microwave-Assisted Intramolecular Ullmann Diaryl Etherification as the Post-Ugi Annulation for Generation of Dibenz[b,f][1,4]oxazepine Scaffold.
abstract: A sequence of the Ugi four-component reaction (U-4CR) and microwave-assisted intramolecular Ullmann etherification has been established for efficient generation of a dibenz[b,f][1,4]oxazepine scaffold. The U-4CR, using 2-aminophenols and 2-bromobenzoic acids or 2-bromobenzaldehydes as the inputs, was carried out in MeOH at 50-60 °C for 2-3 days to form a collection of 22 linear products in 46-90% yields. A microwave-assisted intramolecular Ullmann etherification was then used to transform these acyclic U-4CR products into the cleft-shaped 6/7/6-fused tricyclic heterocycles. The intramolecular Ullmann diaryl ether formation was catalyzed by 10 mol % of CuI and 30 mol % of N,N-dimethylglycine hydrochloride (DMG·HCl) in the presence of Cs2CO3with microwave irradiation (150 °C, 30 min) to furnish dibenz[b,f][1,4]oxazepin-11(10H)-ones and dibenz[b,f][1,4]oxazepin-11(10H)-carboxamides in 64-100% yields.
authors: Laboratory of Asymmetric Catalysis and Synthesis, Department of Chemistry, Zhejiang University , Hangzhou 310027, P. R. of China.
authors: Jianyu
authors: J
authors: Shi
authors: Laboratory of Asymmetric Catalysis and Synthesis, Department of Chemistry, Zhejiang University , Hangzhou 310027, P. R. of China.
authors: Jinlong
authors: J
authors: Wu
authors: Laboratory of Advanced Catalysis and Synthesis, Department of Chemistry, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong SAR, P. R. of China.
authors: Chengsen
authors: C
authors: Cui
authors: Laboratory of Asymmetric Catalysis and Synthesis, Department of Chemistry, Zhejiang University , Hangzhou 310027, P. R. of China.|Laboratory of Advanced Catalysis and Synthesis, Department of Chemistry, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong SAR, P. R. of China.
authors: Wei-Min
authors: WM
authors: Dai