A Metal-Free Approach Toward Saturated N-Propargyl Heterocycles via an Annulation/Decarboxylative Coupling Sequence

A three-component reaction of a 1,2-amino alcohol or 1,3-amino alcohol with a formaldehyde solution and a propiolic acid was developed and studied. This new strategy provided an efficient access to biologically and synthetically important N-propargyl oxazolidines, 1,3-oxazinanes and thiazolidine bearing a diverse range of substituents in good yields. The transformation involves a cascade process that begins with an annulation and is followed by the metal-free decarboxylative coupling.