A Brønsted acid catalyzed C–H functionalization of vinyldiazoacetates with 3-hydroxyisoindolinone is developed. This methodology provides a general access to E-substituted isoindolinone vinyldiazo compounds in good yields and excellent diastereoselectivities with broad substrate generality under mild conditions, and with 4-substituted 2-diazo-3-butenoates produces fused bicyclic pyrrolidines. The reaction generally involves addition of the N-acyl ketiminium electrophile, formed from the 3-hydroxyisoindolinone, to the vinylogous position of the vinyldiazo compound resulting in vinyldiazonium ion intermediates that undergo deprotonation to new vinyldiazo compounds or ring closure to fused bicyclic pyrrolidines.
Key words
Brønsted acid catalysis - vinyldiazo compound - electrophilic addition - C–H functionalization - heterocycles
