Structure Identification: |
Chemistry. 2015 Jul 27;21(31):11152-7. | Highly trans-selective arylation of Achmatowicz rearrangement products by reductive γ-deoxygenation and Heck-Matsuda reaction: asymmetric total synthesis of (-)-musellarins A-C and their analogues[Pubmed: 26104266 ] | Fully functionalized pyranuloses derived from Achmatowicz rearrangement (AR) are versatile building blocks in organic synthesis. However, access to trans-2,6-dihydropyrans from pyranuloses remains underexplored. METHODS AND RESULTS: Herein, we report a new two-step trans arylation of AR products to access 2,6-trans-dihydropyranones. This new trans-arylation method built on numerous plausible, but unsuccessful, direct arylation reactions, including Ferrier-type and Tsuji-Trost-type reactions, was finally enabled by an unprecedented, highly regioselective γ-deoxygenation of AR products by using Zn/HOAc and a diastereoselective Heck-Matsuda coupling. The synthetic utility of the reaction was demonstrated in the first asymmetric total synthesis of (-)-Musellarin A, (-)-musellarin B, (-)-Musellarin C and 12 analogues in 11-12 steps.
CONCLUSIONS:
The brevity and efficiency of our synthetic route permitted preparation of enantiomerically pure musellarins and analogues (>20 mg) for preliminary cytotoxicity evaluation, which led us to identify two analogues with three-to-six times greater potency than the musellarins as promising new leads. |
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