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
