I2-DMSO mediated tetra-functionalization of enaminones for the construction of novel furo[2′,3′:4,5]pyrimido[1,2-b]indazole skeletons via in situ capture of ketenimine cations

The first-ever synthesis of the unknown furo[2′,3′:4,5]pyrimido[1,2-b]indazole skeleton was demonstrated based on the undiscovered tetra-functionalization of enaminones, with simple substrates and reaction conditions. The key to realizing this process lies in the multiple trapping of the in situ generated ketenimine cation by the 3-aminoindazole, which results in the formation of four new chemical bonds and two new rings in one pot. Moreover, The products of this new reaction were found to exhibit aggregation-induced emission (AIE) without modification.