Co(III)-Catalyzed Coupling of Enaminones with Oxadiazolones for Imidazole Synthesis

Skeleton speciation-oriented synthesis as the conventional wisdom of synthetic methodology development prioritizes skeleton as the center of attention for organic speciation, the creation of organic species with differentiated structure-defining feature. The passive as-is assembly of appendages as a secondary accessory inevitably leads to the convergence of appendage pattern on skeleton. We report herein a synthetic practice of appendage speciation-oriented synthesis, emphasizing appendages as the focal point for organic speciation. This synthetic modality seeks, proactively, the maximization of type-, position-, and configuration-variance of appendages through both in situ and ex situ appendage speciation. A Co(III) catalytic protocol in accord with this synthetic modality has been established for coupling of enaminones and oxadiazolones to imidazoles, allowing the achievement of full position-variance of appendages. This translates to expanded reaction and structural development scope and can provide a fertile ground for productive organic synthesis.