Regioselective Formation of Substituted Indoles: Formal Synthesis of Lysergic Acid
Gary L Points1, Kenneth T Stout1, Christopher M Beaudry1
1Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR, 97333, USA.
Abstract:
A Diels-Alder reaction-based strategy for the synthesis of indoles and related heterocycles is reported. An intramolecular cycloaddition of alkyne-tethered 3-aminopyrones gives 4-substituted indolines in good yield and with complete regioselectivity. Additional substitution is readily tolerated in the transformation, allowing synthesis of complex and non-canonical substitution patterns. Oxidative conditions give the corresponding indoles. The strategy also allows the synthesis of carbazoles. The method was showcased in a formal synthesis of lysergic acid.
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