A novel and direct oxidative spirocyclization of arylpropiolamides with sulfonylhydrazides leading to 3-sulfonated azaspiro[4,5]trienones has been developed under metal-free conditions. The reaction is performed in a tandem manner constituted by the sequential sulfonylation of alkynes, ipso-carbocyclization, dearomatization, hydration, and oxidation processes, providing a convenient and efficient approach to various sulfonated azaspiro[4,5] trienones of biological importance.

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Near infrared (NIR) persistent phosphors can exhibit NIR emission for a long period of time after the remove of irradiation, and they have attracted much attention since the demonstration that NIR persistent luminescent nano-sized particles can be used for in vivo imaging. Here, a new NIR persistent luminescence material of lithium substituted MgGa2O4:Cr3+ (termed as MGO:Cr3+, Li+) has been successfully synthesized by sol–gel processing. The MGO:Cr3+, Li+ mainly consists of ∼40–100 nm nanocrystals, which are of single crystalline with excellent crystallinity. Li+ ions occupying the tetrahedral sites (Mg site) does not significantly affect the crystal structure, but it induces a broader band gap. In the processing of substitution for the Mg2+ site by Li+, oxygen vacancies appear that can efficiently store the excited electrons by UV light irradiation and contribute to the improved persistent luminescence. Mg vacancy arising from a higher calcination temperature tends to store visible light, which also contributes to the enhanced afterglow intensity.

Metal-Free Oxidative Spirocyclization of Alkynes with Sulfonylhydrazides Leading to 3-Sulfonated Azaspiro [4,5]trienones. -The tandem process for the preparation of the biologically important scaffolds includes sulfonylation of the alkyne substrates, ipso-carbocyclization, dearomatization, hydration and oxidation. An N-methyl substituent is crucial for a successful reaction. p-Substituted N-arylpropiolamides such as (IV) release the substituent to produce the desired spiro-trienone system [cf. (IIIa)]. -(WEN, J.; WEI, W.; XUE, S.; YANG, D.; LOU, Y.; GAO, C.; WANG*, H.; J. Org. Chem. 80 (2015) 10, 4966-4972, http://dx.doi.org/10.1021/acs.joc.5b00361 ; Sch. Chem. Chem. Eng., Qufu Nom. Univ., Qufu 273165, Peop. Rep. China; Eng.) -Lehmann 40-111