Synthesis of 2‐Arylpyrimido[4,5‐b]porphyrins via Cyclization Reaction with Ammonia

Abstract

AbstractA facile synthetic strategy for the synthesis of a new series of β,β’‐fused 2‐arylpyrimido[4,5‐b]porphyrins has been developed by using condensation cyclization reaction with ammonia. 2‐Aroylamino‐3‐formylporphyrins were synthesized from 2‐aroylaminoporphyrins under Vilsmeier–Haack reaction conditions, which were then efficiently converted to the corresponding 2‐arylpyrimido[4,5‐b]‐5,10,15,20‐tetrakis(4‐chlorophenyl)‐porphyrins via a condensation cyclization reaction. The nickel(II), copper(II), free‐base and zinc(II) analogues of 2‐arylpyrimido[4,5‐b]porphyrins were successfully synthesized in 65–72 % yields and structurally characterized on the basis of spectral data analysis. On photophysical evaluation, 2‐arylpyrimido[4,5‐b]porphyrins demonstrated a 12–19 nm bathochromic shift in their electronic absorption spectra and up to 10 nm red shift in their emission spectra as compared to the simple meso‐(tetrakis(4‐chlorophenyl))porphyrins due to the extended π‐conjugation.