Catalytic Enantioselective Approaches to the oxa-Pictet–Spengler Cyclization and Other 3,6-Dihydropyran-Forming Reactions

Abstract This Short Review provides an analysis of the state-of-the-art in catalytic enantioselective oxa-Pictet–Spengler cyclizations. Also discussed are other catalytic reactions providing access to enantio­enriched isochromans and tetrahydropyrano[3,4- b ]indoles. Context is provided and remaining challenges are highlighted.