Synthesis of 1,4-Dihydroquinolines and 4H-Chromenes via Organocatalytic Domino Aza/Oxa-Michael/1,6-Addition Reactions of para-Quinone Methides and Ynals.

An organocatalytic domino aza/oxa Michael/1,6-addition reaction of ortho-tosylaminophenyl or ortho-hydroxyphenyl-substituted para-quinone methides and ynals has been developed. In the presence of 20 mol % of morpholine, this unprecedented cascade reaction occurs readily in good yield (up to 99%), providing a highly efficient synthetic approach to synthetically valuable 1,4-dihydroquinolines and 4H-chromenes.