(4+2) cyclization of aza-o-quinone methides with azlactones: construction of biologically important dihydroquinolinone frameworks

A base-promoted (4 + 2) cyclization of aza-o-quinone methides (aza-o-QMs) in situ generated from N-(o-chloromethyl)aryl amides was established. In this approach, azlactones were utilized as competent two-atom reaction partners to undergo (4 + 2) cyclization with aza-o-QMs, which afforded a series of dihydroquinolinone derivatives in overall good yields (up to 98%). This protocol has not only advanced the development of aza-o-QM-involved reactions, but also offered a useful method for constructing biologically important dihydroquinolinone frameworks.

Automated summary

A base-promoted cyclization method has been developed for generating aza-o-quinone methides from N-(o-chloromethyl)aryl amides, which react with azlactones to produce dihydroquinolinone derivatives in good yields (up to 98%). This approach not only advances reactions involving aza-o-quinone methides, but also provides a useful strategy for constructing biologically important dihydroquinolinone frameworks.