Applications de la Chimie Radicalaire des Xanthates : Synthèse d'Alcaloïdes d'Origine Marine ; Synthèse de Thiéno2,3-bthiopyranones ; Synthèse de Thioéthers Aryliques ; Approche à la Synthèse Totale du (+)-Maritimol.

摘要

We have developed a useful synthetic β-keto γ-xanthyl phosphonate that is able to create two new carbon-carbon bonds in both a radical and an ionic manner. We have shown that it adds to various olefins in xanthate radical transfer reactions and that the resultant compounds undergo HWE olefination to form α,β-unsaturated ketones. Moreover, we successfully demonstrated its high conjunctivity by completing the first total synthesis of antimicrobial xestamines C, E, and H. We have also developed a facile and highly efficient one-pot synthetic route toward functionalized 2,3,5,6-tetrahydro-thieno[2,3-b]thiopyran-4-ones from easily accessible β-keto ε-xanthyl phosphonates. A broad molecular diversity around the thieno[2,3-b]thiopyran-4-one scaffold could be introduced in only two steps from simple β-keto γ-xanthyl phosphonate. The syntheses of novel and unprecedented spiro thieno[2,3-b]thiopyran-4-ones were also readily achieved. We have also developed a novel one-step, radical approach to aryl thioethers. A number of xanthates were successfully transformed into the corresponding aryl thioethers. The easy access to valuable vinylsilanes in only three steps from simple xanthate adducts is worthy of note and underscores the synthetic potential of this functional group exchange process. We have also established a fast entry into the stemodane natural product family by using the radical transfer technology. A late intermediate of a model of maritimol has been prepared in only 9 steps from commercially available 4,4-dimethylcyclohexenone. Furthermore, we are currently working on the asymmetric synthesis of (+)-maritimol and an advanced intermediate has already been prepared.