Catalyst-Free Synthesis of Chromane-Type N,O-Acetals via Intramolecular Addition of Phenols to Enamines
作者:Vitaly A. Osyanin、Dmitry V. Osipov、Irina V. Melnikova、Kirill S. Korzhenko、Irina A. Semenova、Yuri N. Klimochkin
DOI:10.1055/s-0040-1707209
日期:2020.12
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