Novel synthesis of tetrahydro-β-carbolines and tetrahydroisoquinolines via three-component reaction using hexagonally ordered mesoporous AlSBA-15 catalysts

Tryptamine, aryl aldehyde, and benzyl chloride undergo smooth coupling using well-ordered mesoporous AlSBA-15 catalyst with hexagonal porous structure in acetonitrile at 80 °C to furnish tetrahydrocarbolines in good yields with a high selectivity. This reaction also proceeds with homoveratrylamine to give the corresponding tetrahydroisoquinolines. A variety of aryl and heteroaryl aldehydes have also been used for producing tetrahydrocarbolines in high yields. This AlSBA-15-promoted Pictet–Spengler reaction provides a mild alternative to the traditional Brönsted or Lewis acids typically employed for the preparation of tetrahydrocarbolines and tetrahydroisoquinolines.