Photo‐Induced Homologation of Carbonyl Compounds for Iterative Syntheses

We describe a photo-induced reaction for the in situ generation of highly reactive alkyl diazo compounds from carbonyl precursors via photo-excitation N-tosylhydrazone anions. The intermediates undergo efficient C–H insertion aldehydes, leading to productive synthesis aldehydes and ketones. method is applicable iterative densely functionalized through sequential trapping species with various aldehydes. proceeds without need any catalyst by light irradiation features high functional group tolerance. More than 70 examples, some performed on gram-scale, demonstrate broad applicability this sequence synthesis.