Switchable solvent-controlled divergent synthesis: an efficient and regioselective approach to pyrimidine and dibenzo[b,f][1,4]oxazepine derivatives†
Herein an efficient and regioselective method for the divergent synthesis of pyrimidine and dibenzo[b,f][1,4]oxazepine (DBO) derivatives from the same starting materials was developed. The selectivity can be rationally tuned via the judicious choice of reaction solvents. With 1,4-dioxane used as the solvent, 2-pyrimidinyloxy-N-arylbenzylamines (O-substituted pyrimidines) were obtained in excellent yields, whereas use of dimethyl sulfoxide (DMSO) as solvent afforded N-(2-hydroxybenzyl)-N-phenylpyrimidin-2-amines (N-substituted pyrimidines) in excellent yields, or DBO derivatives in moderate to excellent yields. The easily-accessible substrates and operational simplicity make the process suitable for further exploration. The reaction mechanism involved the SNAr reaction and Smiles rearrangement as key steps.