A practical method for the synthesis of lycorine-type alkaloids with cis-B/C ring structure has been developed. Based on the reactions of aminocyclization, palladium-mediated arylation and especially cyclopropyl ring-opening rearrangement, the synthesis of anhydrocaranine, (±)-γ-lycorane and putative (±)-amarbellisine was accomplished.
Dynamic metasurfaces provide exciting opportunities for spatial light modulation with ultra‐compact footprint and high resolution. Designs reported so far typically suffer from efficiency problem due to the strong coupling between amplitude and phase modulation. Huygens metasurface design eliminates the back propagation with interference of dual resonances, offering a potential solution for phase‐only modulation. However, the intrinsic dispersion mismatch between the dual modes restricts this design to a highly limited bandwidth. Here, a dynamic phase‐change metasurface design that enables transmissive phase modulation covering over 240° with high‐level transmisstance maintained over 0.8 and a large operation bandwidth of 80 nm ranging from 1516 to 1596 nm, is presented. To verify the potential usage of this design, a multi‐state phase‐change control scheme that enables quasi‐continuous phase modulation is further provided. The key feature of this design is the leverage of congener Huygens concept. Judicious incorporation of lossless phase‐change material (PCM) with congener Huygens metasurface allows wideband holding of Huygens condition, which provides a perfect platform to simultaneously address the efficiency and bandwidth problems. This novel feature represents a meaningful step forward to integrate spatial light modulation.
Total Synthesis of Lycorine-Type Alkaloids by Cyclopropyl Ring-Opening Rearrangement. -Three lycorine-type alkaloids are prepared by a new synthetic method. A newly developed cyclopropyl ring-opening rearrangement allows the practical synthesis of anhydrocaranine (I), racemic -lycorane (II), and putative racemic amarbellisine (III). The structures of the synthesized compounds are confirmed by spectroscopic data. Compound (III) turns out to be a different isomer to the natural amarbellisine. -(LIU, D.; AI, L.; LI, F.; ZHAO, A.; CHEN, J.; ZHANG, H.; LIU*, J.; Org.
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