DDQ Oxidation of 6- or 8-Allyl-7-hydroxycoumarins. A New Synthesis of Benzodipyrandiones and Furobenzopyranones

Abstract

A novel synthesis of 2H,8H-benzo[1,2-b:3,4-b′]dipyran-2,8-diones, 2H,8H-benzo[1,2-b:5,4-b′]dipyran-2,8-diones, 2H-furo[2,3-h][1]benzopyran-2-ones, and 7H-furo[3,2-g][1]benzopyran-7-ones was achieved by developing 2-pyrone and furan ring over coumarin. 6- or 8-Ally-7-hydroxycoumarins on oxidation with 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) afforded benzodipyrandiones and furobenzopyranones. The structures of the compounds now synthesized were established by analytical, spectral, and comparison with authentic samples prepared by the known procedures.

Chemistry and Biology of Mycotoxins and Related Fungal Metabolites

“…These elegant transformations, which were elucidated by careful reactivity analysis of the given systems, highlight the power of cascade reactions in targeting complex molecular structures. 992 With these transformations in hand, the stage was now set for the total synthesis of skyrin natural products (9,409,410). Indeed, Nicolaou and co-workers reported the total synthesis of rugulosin (410, Figure 20) and 2,2′-epi-cytoskyrin A (417) shortly after the discovery of the cytoskyrin cascade.…”

Furocoumarins in Medicinal Chemistry. Synthesis, Natural Occurrence and Biological Activity

“…The cyclization to the dihydrofurocoumarin is performed in an acidic medium (usually sulfuric acid) and the product of this reaction is then d e h y d r o g e n a t e d [31,32]. These steps can be performed in reverse order by oxidation with OsO 4 [26] or O 3 [27,33] followed by thermal cyclization with PPA [25] or p -TsOH [26,27].…”