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A visible light-mediated, I2-catalyzed intermolecular transformation of alkenes, conjugated dienes, styrenes and alkynes to isooxazoline and isoxazole motifs with a-nitrocarbonyls and analogs is reported. The reaction is also applicable to 1,1-disubstituted terminal, 1,2-disubstituted internal and trisubstituted alkenes, and tolerates a range of functional groups including epoxides, heterocycles, phosphates, free alcohols and thiocyanates. Mechanistic studies reveal that a-nitrocarbonyls are first converted to -carbonyl radicals followed by their conversion to acyl nitrile oxides, which subsequently undergo [3 + 2] dipolar cycloaddition reactions with the unsaturated molecules. 

Abstract Digital in-line holography (DIH) is an established method to image small particles in a manner where image reconstruction is performed computationally post-measurement. This ability renders it ideal for aerosol characterization, where particle collection or confinement is often difficult, if not impossible. Conventional DIH provides a gray-scale image akin to a particle’s silhouette, and while it gives the particle size and shape, there is little information about the particle material. Based on the recognition that the spectral reflectance of a surface is partly determined by the material, we demonstrate a method to image free-flowing particles with DIH in color with the eventual aim to differentiate materials based on the observed color. Holograms formed by the weak backscattered light from individual particles illuminated by red, green, and blue lasers are recorded by a color sensor. Images are reconstructed from the holograms and then layered to form a color image, the color content of which is quantified by chromaticity analysis to establish a representative signature. A variety of mineral dust aerosols are studied where the different signatures suggest the possibility to differentiate particle material. The ability of the method to resolve the inhomogeneous composition within a single particle in some cases is shown as well. 

Abstract We disclose a Ni‐catalyzed cyclization/alkylmetal interception reaction in which products are readily linearized to permit regiodefined alkene dicarbofunctionalization. This method offers a convenient route to access 1,2‐oxasilolane heterocycles, 3‐hydroxysilanes and 4‐arylalkanols with the formation of C(sp³)−C(sp³) bonds at primary and secondary alkyl carbon centers. In this reaction, a silicon‐oxygen (Si−O) bond functions as a detachable linker that can be delinked with several hydride, alkyl, aryl and vinyl nucleophiles to create profusely functionalized 3‐hydroxysilanes. A silicon motif in the cyclic C(sp³)−Si−O construct in 1,2‐oxasilolane heterocycles can also be selectively deleted by Pd‐catalyzed hydrodesilylation affording Si‐ablated linear alcohol products reminiscent of vicinal ethylene dicarbofunctionalization with C(sp³) and C(sp²) carbon sources. 

Abstract We demonstrate that 2‐alkenylarylaldimines and ketimines undergo thermal 6π‐azaelectrocyclization to generate a wide range of azabicyclico‐quinodimethanes (o‐QDMs). Theseo‐QDMs exist as a hybrid of a diene and a benzylic diradical. The diradical nature was confirmed by their ability to undergo dimerization and react with H‐atom donor, 2,2,6,6‐tetramethylpiperidin‐1‐yl)oxyl (TEMPO) and O₂. In addition, the interception of the diradicaloido‐QDMs by H‐atom transfer was used to synthesize five tetrahydroisoquinoline alkaloids and related bioactive molecules. The diene form can undergo [4+2] cycloaddition reactions with different dienophiles to generate bridged azabicycles in high endo:exo selectivity. The azabicyclico‐QDMs can be generated for [4+2] cycloaddition from a wide range of electronically and sterically varied 2‐alkenylarylimines, including mono, di, tri and tetrasubstituted alkenes, and imines derived from arylamine, alkylamine (1°, 2°, 3°), benzylamine, benzylsulfonamide andBoc‐amine. 

This work applies digital holography to image stationary micro-particles in color. The approach involves a Michelson interferometer to mix reference light with the weak intensity light backscattered from a distribution of particles. To enable color images, three wavelengths are used, 430, 532, and 633 nm, as primary light sources. Three separate backscattered holograms are recorded simultaneously, one for each wavelength, which are resolved without spectral cross talk using a three-CMOS prism sensor. Fresnel diffraction theory is used to render monochrome images from each hologram. The images are then combined via additive color mixing with red, green, and blue as the primary colors. The result is a color image similar in appearance to that obtained with a conventional microscope in white-light epi-illumination mode. A variety of colored polyethylene micro-spheres and nonspherical dust particles demonstrate the feasibility of the approach and illustrate the effect of simple speckle-noise suppression and white balance methods. Finally, a chromaticity analysis is applied that is capable of differentiating particles of different colors in a quantitative and objective manner.