BF3·OEt2-Mediated C-C Bond-Forming Reaction of α-Hydroxyketene-(S,S)-acetals with Active Methylene Compounds and Its Application in the Synthesis of Substituted 3,4-Dihydro-2-pyridones

Abstract

The C-C bond-forming reaction between α-hydroxy­ketene-(S,S)-acetals 2 and active methylene compounds is described. Mediated by boron trifluoride etherate (BF3·OEt2), a series of C-C bond coupling products, 2-(2-acetyl-1-methyl-3-oxobutyl)-N-aryl-3,3-bis(ethylthio)acrylamides 3 was obtained in high to excellent yields by the reaction of 2a-e (R1 = Ar) with acetylacetone. Various N-aryl-substituted 3,4-dihydropyridones 5 were prepared in high yields from 3 via a two-step procedure. Upon the reaction of 2f (R1 = H) with active methylene compounds, 3,4-dihydropyridones 6 and/or 7, were obtained in a one-pot reaction with moderate to good yields.