A perspective of one-pot pyrrole-aldehyde condensations as versatile self-assembly processes

Regarded as the classic one-pot synthetic route to symmetrical porphyrins for well over half a century, pyrrole-aldehyde cyclocondensations have yielded a cornucopia of nonporphyrin macrocycles, such as N-confused porphyrins, corroles, sapphyrins, and expanded porphyrins, and have thus emerged as versatile self-assembly processes. A highlight in this field is the remarkably general one-pot corrole synthesis. The manifold of intermediates generated in the anaerobic phase of a Lindsey-type synthesis have been viewed as a dynamic covalent self-assembly system. This raises the possibility that the addition of a suitable host may alter the equilibrium concentrations of these intermediates by molecular recognition and related phenomena and thus determine the major product formed after oxidative quenching.