Enantioselective total synthesis of pinnaic acid and halichlorine
Shu Xu1, Daisuke Unabara, Daisuke Uemura
1Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Sendai 980-8577 (Japan), Fax: (+81) 22-217-6204.
Abstract:
The enantioselective total synthesis of the bioactive marine natural products pinnaic acid and halichlorine is reported in detail. Our total synthesis features the construction of the five-membered ring and C9 and C13 stereogenic centers through a palladium-catalyzed trimethylenemethane [3+2] cyclization; the installation of the nitrogen atom through a regioselective Beckmann rearrangement of a poorly reactive ketone; the stereoselective cyclization of the spiro ring through a four-step, one-pot hydrogenation-cyclization; and efficient connection of the sterically hindered lower chain through a reduced-pressure cross olefin metathesis reaction.
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