Synthesis of Pyrrole-2-carbaldehyde Derivatives by Oxidative Annulation and Direct C sp 3-H to C═O Oxidation.

An efficient and practical de novo synthesis of pyrrole-2-carbaldehyde skeletons featuring oxidative annulation and Csp 3-H to C═O oxidation is presented, exemplified by the preparation of pyrrole-2-carbaldehyde derivatives from aryl methyl ketones, arylamines, and acetoacetate esters. Preliminary mechanistic investigations indicate that the aldehyde oxygen atom originates from oxygen. Moreover, the developed scalable approach provides a distinct advantage over traditional oxidative functionalization of C-H moieties, avoiding the use of stoichiometric quantities of hazardous oxidants.