A Solvent-Regulated Dediazotized Oxygenation of Α-Aryl Α-Diazoesters and 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ)

A new metal-free, solvent-regulated dediazotized oxygenation of alpha-aryl alpha-diazo esters and 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) is reported. The reaction of alpha-aryl alpha-diazo esters and DDQ in 2:1 molar ratio in dichloromethane (DCM) underwent double dediazotized O-H bond insertion reactions to access alpha, alpha'-(1,4-phenyldioxy)diesters as major products, whereas a series of structurally complex alpha,alpha-diaryloxy esters were provided with moderate to good yields when the reaction of these substrates in 3:2 molar ratio in dichloroethane (DCE) proceeded through a double dediazotized O-H bond insertion and dediazotized deoxygenation cascade. The controlled experiments confirmed that the hydrogen atom is from water during O-H bond insertion process. In addition, the reaction featured mild conditions, simple operation and controllable chemoselectivity without any catalyst.