l-Proline-catalyzed diastereoselective synthesis of cis-isoquinolonic acids and evaluation of their neuroprotective effects

l-Proline efficiently catalyzes the one-pot, three-component reaction of homophthalic anhydride, amines, and aldehydes in CH3CN at room temperature, to afford the corresponding cis-isoquinolonic acids in high yields and with excellent diastereoselectivities. The synthesized compounds are screened for neuroprotective activities.