Model studies for the stereoselective construction of the BC-ring of armatol F based on Ireland-Claisen rearrangement and relay ring-closing olefin metathesis
triterpene, has a fused tricyclic ether moiety (BCD-ring) with an unusual cis ring junction at C18–C19 between the C- and D-rings. En route to the total synthesis of armatol F, the stereoselective construction of the C18 and C19 stereocenters by Ireland-Claisen rearrangement and the formation of the C-ring by relay ring-closing olefin metathesis were established through the synthesis of monocyclic (C-ring)
The EF-ring segment of ciguatoxin 3C, a causative toxin of ciguatera fish poisoning, was synthesized in three major steps: 1,4-addition for the C20O-C27 bond connection, chirality transferring anti selective [2,3]-Wittig rearrangement for the construction of the anti-2-hydroxyalkyl ether part, and ring-closing olefin metathesis for the F-ring formation.
(4 + 2) Annulation of Cl<sup>–</sup>NH<sub>3</sub><sup>+</sup>CH<sub>2</sub>SiMe<sub>2</sub>CH<sub>2</sub>Cl and Propynones for the Synthesis of 1,3-Azasilinones
作者:Chang Ma、Yu Fan、Chunmei Zheng、Lu Gao、Wanshu Wang、Bowen Ke、Zhenlei Song