Ruthenium（Ⅱ）-catalyzed Coupling Reaction Of 2-arylquinazolone With Ethylene Carbonate

Transition metal-catalyzed direct C-H bond functionalization is one of most efficient and straightforward approach for the assembly of C-C and C-hetero bond in organic chemistry.Recently,ruthenium（Ⅱ）complexes have great potential in C-H bond functionalization due to their high catalytic activity,low-cost,good group tolerance and excellent regionselective.We firstly introduce a ruthenium（II）-catalyzed C_Ar-H functionalization with alkyne,olefin,alkyl halides,and isocyanates.Subsequently,a ruthenium（II）-catalyzed C-H functionalization and intramolecular reaction of arene with vinylene carbonate is reported.This paper reports a Ru（II）-catalyzed direct and efficient method of 2-arylquinazolinones with vinylene carbonate to synthesize fused quinazolinones under argon atmosphere,through a sequential C-H activation,β-CO₂elimination,annulative C-N formation process.Examining steric hindrance and electronic effects demonstrates a wide scope of substrates with excellent functional-group tolerance.A gram scale experiment can be carried out smoothly and the target product can be obtained in good yield under a reduced loading of[Ru（p-cymene）Cl₂]₂.In order to gain insight into the reaction mechanism,some control experiments were investigated.First,the H/D exchange experiments revealed that C-H bond activation is a reversible process.The experiments of kinetic isotope effect（KIE）demonstrated that C-H bond activation is probably involved in the turnover-limiting step.The capture of the key intermediate indicated that the vinylene carbonate act as an ethynol equivalent through the decarboxylation process without external oxidant in this catalytic system of C-H activation.