Brønsted Acid-Catalyzed Insertion of Aryldiazoacetates to sp2 Carbon−CHO Bond: Facile Construction of Chiral All-Carbon Quaternary Center

Aryldiazoacetates could be formally inserted into the carbon−carbon bond of the Brønsted acid-activated aromatic and α,β-unsaturated aldehydes. Use of phenylmenthyl esters allowed the asymmetric induction at the inserted all-carbon quaternary carbon center with the excellent stereoselectivities.