One‐Pot Synthesis of cis ‐Isoquinolonic Acid Derivatives via Three‐Component Reaction of Homophthalic Anhydride with Aldehydes and Amines using Ytterbium(III) Triflate as Catalyst

Ytterbium(III) triflate efficiently catalyzes the one‐pot reaction of homophthalic anhydride with aldehydes and amines at ambient temperature to afford the corresponding cis ‐isoquinolonic acid derivatives in good to excellent yields with high diastereoselectivity. This method provides a novel and much improved modification of the three‐component reaction in terms of mild reaction conditions, short reaction times, clean reaction profiles, small quantity of catalyst, and simple work‐up procedure. Another important feature of this method is that the catalyst can be easily recovered from the aqueous layer after the reaction and can be reused with no loss of activity.