Microwave-Assisted Intramolecular Ullmann Diaryl Etherification as the Post-Ugi Annulation for Generation of Dibenz[ b , f ][1,4]oxazepine Scaffold
2016; American Chemical Society; Volume: 81; Issue: 21 Linguagem: Inglês
10.1021/acs.joc.6b01398
ISSN1520-6904
AutoresJianyu Shi, Jinlong Wu, Chengsen Cui, Wei‐Min Dai,
Tópico(s)Synthesis and pharmacology of benzodiazepine derivatives
ResumoA 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 Cs2CO3 with 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.
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