A New Synthesis of Thioflavanones from Thiosalicylic Acid

Two-Component Assembly of Thiochroman-4-ones and Tetrahydrothiopyran-4-ones Using a Rhodium-Catalyzed Alkyne Hydroacylation/Thio-Conjugate-Addition Sequence

“…Thiochromanones and related heterocycles, notably S , S -dioxide derivatives and unsaturated variants, are present in a number of medicinally relevant molecules (Scheme c), and as such we envisaged a general synthetic route that would allow access to a broad range of related S -heterocycles. Our approach is shown in Scheme b and involves chelate-controlled alkyne hydroacylation followed by an acid triggered thio-conjugate addition . Although encouraging precedent is provided from our own reports of hydroquinolone synthesis, and Stanley’s chroman-4-one chemistry, both of these sequences are limited to aryl aldehyde substrates, thus constraining the structural variation accessible in the products.…”