Cu-Catalyzed decarboxylative annulation of N -substituted glycines with 3-formylchromones: synthesis of functionalized chromeno[2,3- b ]pyrrol-4(1 H )-ones.

A novel protocol was developed for preparing functionalized chromeno[2,3 -b ]pyrrol-4(1 H )-ones 3 (CMPOs) from 3-formylchromones with N -substituted glycine derivatives. The method entailed decarboxylative annulation of the acyl group of 3-formylchromones by simply heating a mixture of substrates 1-2 and toluene oxidized by 2-di- tert -butyl peroxide (DTBP) and catalyzed by CuBr. As a result, a series of CMPOs 3 were produced via a cascade reaction. This protocol can be used to synthesize functionalized CMPOs via combinatorial and parallel syntheses in a one-pot reaction rather than a tedious multi-step reaction.