The condensation of asymmetric β-diketones with α-oximinoacetoacetate esters affords pyrroles regioselectively. The mechanism of the regioselectivity is studied using 13C-NMR spectroscopy. Pyrrole having a neopentyl group at the 4-position is synthesized by the method, and further converted to a steric hindered porphyrin in good yield.
