Recent Advances in the Synthesis of 3,4-Dihydropyran-2-Ones Organocatalyzed by N-Heterocyclic Carbenes

Abstract

In recent years, N-heterocyclic carbenes (NHC) have gained recognition as versatile molecules capable of acting as organocatalysts in various reactions, particularly through the activation of aldehydes via Breslow-type adducts. This organocatalytic activation has enabled the production of numerous 3,4-dihydropyran-2-ones and related derivatives. In this review, we provide an overview of the production of 3,4-dihydropyran-2-ones and derivatives via organocatalytic processes involving NHCs over the past eight years. These processes involve the use of a diverse range of substrates, catalysts, and reaction conditions, which can be classified into [4+2]-and [3+3]-type cycloadditions, primarily aimed at synthesizing this skeleton due to its biological activity and multiple stereocenters. These processes are scaled up to the gram scale, and the resulting products are often directed towards epimerization and functionalization to produce more complex molecules with potential applications in the biological field. Finally, we provide a perspective and the future directions of this topic in organic synthesis.

Isothiourea-Catalyzed Enantioselective Synthesis of trans-3,4-Dihydrothiopyranones: Harnessing Thiochalcones as Original Michael Acceptors

“…Chiral dihydropyranones constitute a class of heterocycles that have attracted particular interest because of their occurrence in pharmaceuticals, as well as in precursors of natural products . Because of their importance, many efforts have been devoted to their efficient catalytic enantioselective synthesis . Surprisingly, the asymmetric access to dihydrothiopyranonestheir sulfur-containing analogueshas been scarcely investigated, despite their promising biological activities .…”