Catalyst-Free Synthesis of Chromane-Type N,O-Acetals via Intramolecular Addition of Phenols to Enamines
V. A. Osyanin, Dmitry V. Osipov, Irina V. Melnikova, Кирилл С. Корженко, Ирина А. Семенова, Yu. N. Klimochkin
Abstract
A new strategy to 2-aminochromanes through catalyst-free cascade reaction of 3-trifluoroacetyl-4H-chromenes and 4H-chromene-3-carbaldehydes with cyclic secondary amines is presented. The reaction proceeds through subsequent 1,4- and 1,2-additions of amine, bimolecular elimination of trifluoroacetamide or formamide, and 6-exo-trig cyclization. The latter stage is a very rare example of addition of phenols to enamines. The obtained semicyclic N,O-acetals were applied as useful precursors for the synthesis of other chromanes.
Topics & Concepts
ChemistryCatalysisIntramolecular forcePhenolsFormamideAmine gas treatingOrganic chemistryCascadeMedicinal chemistryChromatographySynthesis of Indole DerivativesSynthesis of Organic CompoundsSynthesis of heterocyclic compounds