Synthesis of spiro[benzo[d][1,3]oxazine-4,4′isoquinoline]s through a unique [4+1+1] annulation of N-aryl amidines with diazo homophthalimides and O 2 is presented. This unprecedented spirocyclization reaction features readily obtainable substrates, structurally and pharmaceutically attractive products, a cost-free and clean oxygen source, sustainable reaction medium, tolerance of a broad spectrum of functional groups, and an interesting reaction mechanism based on sequential C(sp 2 )−H/ C(sp 3 )−H bond cleavage and oxygen insertion.
In vivo H2 O 2 visualization is crucial for disease diagnosis. Catalytic reactionbased probes show potential in H 2 O 2 detection, yet their in vivo application remains challenging because catalysts always require a specific pH to function and cellular glutathione (GSH) may suppress signaling by depletion of hydroxyl radicals and oxidized substrates. Here, a microenvironment-tailored catalytic nanoprobe (MTCN) comprising Fe 2+ , citric acid (CA), 2,2′-azino-bis(3ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), and downconversion nanoparticles in the liposomal cavity as well as a reference dye in the lipid membrane is reported, which utilizes the selective permeability of the liposomal membrane to offer a favorable pH for Fe 2+ catalyst with the aid of CA and to avoid GSH-triggered signal loss by preventing entry of GSH into the cavity. The MTCN displays a large NIR-II fluorescence (FL) ratio between 1550 and 1080 nm (FL 1550Em,808Ex /FL 1080Em,980Ex ), but a small photoacoustic (PA) ratio between 808 and 1048 nm (PA 808 /PA 1048 ). Upon exposure of MTCN to H 2 O 2 , catalytic conversion of ABTS into its oxidized form ABTS• + with 808 nm absorption causes a noticeable increment in PA 808 /PA 1048 accompanied by an apparent decrement in FL 1550Em,808Ex /FL 1080Em,980Ex , enabling bimodal ratiometric imaging of H 2 O 2 in the tumor and lymphatic metastasis.
In this paper, an efficient synthesis of functionalized 1,3-benzodiazepines
through an unprecedented [5 + 2] annulation of N-aryl
amidines with propargylic esters is presented. The reactions proceed
through Rh(III)-catalyzed C(sp2)−H alkenylation
followed by annulation and deacetoxylation along with cascade C−H/N−H/C−O
bond cleavage and C−C/C−N bond formation. Furthermore,
the cytotoxicity of selected products against several human cancer
cell lines was tested, which demonstrated their good potential for
pharmaceutical applications.
In this paper, an efficient synthesis of 3-spirooxindole 3H-indoles through the coupling and spirocyclization of N-aryl amidines with diazo oxindoles is presented. Mechanistically, the formation of the title products involves...
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