The efficient production of H2O2 from only H2O and O2 was realized by a self-assembled porphyrin-based photocatalyst, and the effect of carboxylic groups in the water oxidation to produce H2O2 was revealed.

We propose in this study an iminium ion/enamine tandem sequence that could efficiently overcome energy barriers encountered in Michael and aldol reactions during [3+2] annulations of acyl pyridines and α,β-unsaturated aldehyde for the construction of diverse indolizine-2-carbaldehydes.