A concise construction of 4-alkynylquinazolines via [4 + 2] annulation of 4-alkynylbenzoxazinanones with acylhydroxamates under transition-metal-free conditions

A concise and highly efficient method for the construction of valuable 4-alkynylquinazolines under transition-metal-free conditions was developed via [4 + 2] annulation of 4-alkynylbenzoxazinanones with acylhydroxamates in good to excellent yields. The reaction featured the use of low-cost bases NaOAc or NaOMe, simple operation and high chemoselectivity. The broad substrate scope and the typical maintenance of high efficiency on a gram scale made this protocol a potentially practical method to synthesize 4-alkynylquinazolines.