Synthesis of tetrahydro-β-carbolinediketopiperazines in [bdmim][PF6] ionic liquid accelerated by controlled microwave heating

Because of their negligible vapor pressures and large dipoles, ionic liquids are excellent media for microwave-accelerated organic reactions. Using low-power microwave irradiation in the new [bdmim][PF6] ionic liquid with temperature controlled at 60degreesC, a three-step synthesis (Pictet-Spengler, Schotten-Baumann, and intramolecular ester amidation) of tetraliydro-beta-carboline-diketopiperazines starting from tryptophan methyl ester was achieved with good isolated yields (49-69%) in only 5 min. (C) 2004 Elsevier Ltd. All rights reserved.