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Asymmetric Total Synthesis of Arcutinidine, Arcutinine, and Arcutine

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posted on 21.08.2019, 14:34 by Shupeng Zhou, Kaifu Xia, Xuebing Leng, Ang Li
We have accomplished the asymmetric total synthesis of arcutinidine, arcutinine, and arcutine, three arcutine-type C20-diterpenoid alkaloids. A pentacyclic intermediate was rapidly assembled by using two Diels–Alder reactions. We developed a cascade sequence of Prins cyclization and Wagner–Meerwein rearrangement to construct the core of arcutinidine, which was then elaborated into an oxygenated pentacycle through a scalable route. Chemoselective reductive amination followed by spontaneous imine formation furnished the pyrroline motif in the final stage. We clarified the S configuration of the α-carbon of the acyl group within arcutine through chemical synthesis and crystallographic analysis.