Synthesis of Polyoxygenated Biphenyls

Background: Construction of biaryls containing polyoxygenated groups via the palladiumcatalyzed Suzuki-Miyaura cross-coupling reaction of aryl halides with organoboronic acids is a very interesting area of research. A number of functionalized polyoxygenated biphenyls have received considerable attention during the past decades, due to their presence as the structural motifs in natural products with diversified biological activities. Due to the particular pharmaceutical interest concerning the specific substitution pattern of a biphenyl scaffold, several synthetic methods have been developed. On the basis of investigation, we developed a novel Suzuki-Miyaura cross-coupling route for preparing polyoxygenated biphenyls. Objective: In the work, we have successfully presented a synthetic route for the synthesis of polyoxygenated biphenyls via Suzuki-Miyaura cross-coupling reaction. Methods: Polyoxygenated biphenyls are prepared in six synthetic steps, included: (1) olefinic migration; (2) Baeyer-Villiger deformation; (3) O-benzylation; (4) olefin oxidative cleavage; (5) regioselective bromination; and (6) Suzuki-Miyaura cross-coupling reaction. Results: A series of novel polyoxygenated biphenyls have been synthesized through a facile strategy. These structures of polyoxygenated biphenyls are determined by 1H and 13C NMR. Three structures of the key products were confirmed by X-ray crystallography. Conclusion: We have successfully presented a synthetic route for the synthesis of polyoxygenated biphenyls via Suzuki-Miyaura cross-coupling reaction of polyoxygenated bromoarenes with different arylboronic acids. This synthesis begins with the starting material, isovanillin, and provides facile routes for preparing two skeletons of chromanones and tetraoxygenated benzenes. Many explorations are anticipated in the near future.