Copper-Catalyzed Synthesis of α-Keto Amides from Sulfoxonium Ylides.

We here described a method to synthesize α-keto amides from simple sulfoxonium ylides and secondary amines under the catalysis of copper. This transformation involved a very simple and clean catalytic system, and the substrates could be extended to aryl, heteroaryl, and tert-butyl sulfoxonium ylides to give diversified α-keto amides with good yields. Additionally, the mechanistic studies indicated that the α-carbonyl aldehyde might be a key intermediate in the reaction system.

Tri-channel metasurface for watermarked structural-color nanoprinting and holographic imaging.

Structural-color nanoprinting, which can generate vivid colors with spatial resolution at subwavelength level, possesses potential market in optical anticounterfeiting and information encryption. Herein, we propose an ultracompact metasurface with a single-cell design strategy to establish three independent information channels for simultaneous watermarked structural-color nanoprinting and holographic imaging. Dual-channel spectrum manipulation and single-channel phase manipulation are combined together by elaborately introducing the orientation degeneracy into the design of variable dielectric nanobricks. Hence, a structural-color nanoprinting image covered with polarization-dependent watermarks and a holographic image can be respectively generated under different decoded environments. The proposed metasurface shows a flexible method for tri-channel image display with high information capacity, and exhibits dual-mode anticounterfeiting with double safeguards, i.e., polarization-controlled watermarks and a far-field holographic image. This study provides a feasible route to develop multifunctional metasurfaces for applications including optical anticounterfeiting, information encryption and security, information multiplexing, etc.