Ultrasound Assisted Pictet-Spengler Synthesis of Tetrahydro-β-Carboline Derivatives

Abstract

The synthesis of twelve tetrahydro-β-carboline derivatives 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k, 3l prepared via the Pictet-Spengler reaction is described. The reaction of tryptamine and a variety of arylaldehydes were carried out under ultrasonic irradiation and trifluoracetic acid catalysis at room temperature. These tetrahydro-β-carbolines have been synthesized in higher yields and shorter reaction times compared to the conventional method. Moreover, the reaction proceeded successfully even employing arylaldehydes with electron-donating or electron-attracting substituents which did not react under conventional method.