Synthetic Studies of Indoles and Related Compounds. XXVII. A New Synthesis of Crenatine from Ethyl Indole-2-carboxylate

Abstract

Crenatine (1a), which is a member of a new class of β-carboline alkaloids having an oxygen functionality at the 4-position, was synthesized starting from ethyl 1-benzylindole-2-carboxylate (12a) via cyclization of an elaborated C₂-subsitituent to the 3-position of the indole nucleus and aluminum chloride-catalyzed debenzylation of the protected indolic nitrogen. 1-Ethyl-4-hydroxy-9-methyl-β-carboline (26b), a positional isomer of crenatine with regard to the methyl group, was also synthesized through the same methodology.