Cooperative photoactivation/Lewis base catalyzed [4+2] annulations of alpha-diazoketones and ortho-amino MBH carbonates to access dihydroquinolinone frameworks

A series of multifunctional dihydroquinolinone frameworks have been synthesized via synergistic catalysis combining photolysis and Lewis base catalysis utilizing in situ generated ketenes from the visible-light-mediated Wolff rearrangement of alpha-diazoketones and ortho-amino MBH carbonates. This powerful [4 + 2] annulation further broadens the application of MBH carbonates in cooperative catalysis and features good compatibility and high efficiency. Furthermore, the control experiments indicate that a synergistic catalysis strategy plays a crucial role in the cycloaddition reaction, and a plausible mechanism is proposed to explain the reaction process.