Abstract

The literature on the syntheses of substituted 1-(indol-3-yl)-1,2,3,4-tetrahydroisoquinoline derivatives is reviewed. Two main synthetic procedures have been applied for these syntheses. One is cross-dehydrogenative coupling, which can furnish various C-3 functionalized indoles; oxidants and/or catalysts are usually needed. Another convenient synthetic method is the aza-Friedel–Crafts alkylation of indole derivatives with dihydroisoquinoline, the main advantage of this being the direct catalyst-free coupling under mild experimental conditions. The review also considers miscellaneous reactions, where the isoquinoline skeleton is achieved in one of the final steps of the synthesis.

Keywords: Isoquinoline, indole, β-carboline, cross-dehydrogenative coupling, aza-Friedel–Crafts alkylation.

Graphical Abstract