One-Pot, Three-Component Coupling Synthesis of [(Benzothiazol-2-ylamino)(aryl)methyl]isoquinolinols under Catalyst- and Solvent-Free Conditions

Abstract A one-pot, three-component coupling procedure has been developed for the synthesis of [(benzothiazol-2-ylamino)(aryl)methyl]isoquinolinols via the reaction of hydroxyisoquinolines, aryl/heteroaryl/aliphatic aldehydes with 2-aminobenzothiazoles under catalyst- and solvent-free conditions. The developed 2′-aminobenzothiazolomethylation procedure is suitable to execute even on a gram scale and has a broad scope. The 2′-aminobenzothiazolomethylated products (Betti bases) were formed through the initial nucleophilic C-attack of hydroxyisoquinolines on aldehydes to generate the ortho-quinone methide (o-QM) as an intermediate, followed by 1,4-aza-Michael addition of 2-aminobenzothiazoles. Betti bases have significance in medicinal chemistry due to their wide range of pharmacological applications and they are useful ligands and catalysts in asymmetric synthesis.