Scope and Limitations of the Domino Vinylogous Aldol/oxa‐Michael Reaction

Abstract

The asymmetric, atom economic reaction of salicylaldehydes with α,β‐unsaturated aldehydes in the presence of an organocatalyst leads to chiral tricyclic chromanes. In this report, the first exploration of heteroatom‐substituted α,β‐unsaturated aldehydes is demonstrated: We present the investigation of the enantioselective domino vinylogous aldol/oxa‐Michael reaction in respect to its scope and limitations. The chiral chromanes arriving from this reaction are highly functionalized and are versatile synthetic intermediates that can further be converted into the respective tetrahydroxanthones with functionalities on the C‐4a position. A new synthetic route to a methyl ester on this position is developed starting with a p‐methoxyphenyl protected alcohol.