ChemInform Abstract: Use of Pictet—Spengler Reaction for the Synthesis of 1,4‐Disubstituted‐1,2,3,4‐tetrahydro‐β‐carbolines and 1,4‐Disubstituted‐β‐carbolines: Formation of γ‐Carbolines.

Abstract

Fused pyridine derivatives R 0450Use of Pictet-Spengler Reaction for the Synthesis of 1,4-Disubstituted--1,2,3,4-tetrahydro-β-carbolines and 1,4-Disubstituted-β-carbolines: Formation of γ-Carbolines. -Best results in the conjugate addition of indole to nitroolefins are achieved performing the reaction under microwave irradiation and loading the reactants on silica gel. Adducts are reduced to tryptamines, which undergo Pictet-Spengler condensation providing new 1,4-disubstituted-β-carbolines. For substrates (VIa,b), further dehydrogenation in refluxing xylene results in the formation of 1,4-disubstituted-γ-carbolines. Treatment of tryptamines (IVe,f) with benzaldehydes affords two regioisomers which are further dehydrogenated in a similar manner. -(KUSURKAR*, R. S.; ALKOBATI, N. A. H.; GOKULE, A. S.; PURANIK, V. G.; Tetrahedron 64 (2008) 8, 1654-1662; Dep. Chem., Univ. Pune, Pune 411 007, India; Eng.) -S. Adam