Enantioselective Cobalt(III)-Catalyzed 4 + 1 Annulation of Benzamides: Cyclopropenes as One-Carbon Synthons

High Resolution Image Download MS PowerPoint Slide A chiral cyclopentadienyl cobalt(III)-catalyzed enantioselective 4 + 1 annulation of N -chlorobenzamides with cyclopropenes is reported. The cobalt catalyst engages in the C–H activation as well as promotes the C–C bond cleavage of the cyclopropene, rendering it as a one-carbon unit for the annulation. The reaction efficiently constructs biologically relevant chiral isoindolinones with selectivities of up to 99:1 er and >20:1 E / Z ratios. The cobalt(III) catalyst displays a unique orthogonal reactivity profile delivering 4 + 1 annulation products, whereas its rhodium(III) homologue engages in the more classical 4 + 2 annulation pattern. Computational studies reveal the origin of these reactivity divergences.