Convenient Synthesis of 1,2,3,4-Tetrahydroisoquinoline-1-carboxylic Acid Derivatives via Isocyanide-Based, Three-Component Reactions

The three-component reactions of 3,4-dihydroisoquinolines, isocyanides, and benzyl chloroformate furnished 2-benzyloxycarbonyl-1,2,3,4-tetrahydroisoquinoline-1-carboxamides in moderate to good yields. Hydrogenolysis or selective hydrolysis of the benzyloxycarbonyl group provided 1,2,3,4-tetrahydroisoquinoline-1-carboxamides, further hydrolysis of which resulted in the corresponding 1,2,3,4-tetrahydroisoquinoline-1-carboxylic acids.