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A transition-metal-free postmodification of the Groebke-Blackburn-Bienayme (GBB) reaction for the synthesis of spiro[chromene-imidazo[1,2-a]pyridin]-3'-imine was discovered. The unusual transformation represents the first example of activation and the reaction of the imidazole carbon atom. In this postcondensational modification, KOt-Bu acts as a base, which, after the isomerization of an alkyne moiety to allene, causes the next unique nucleophilic reaction of the imidazole carbon atom that results in spirocyclic structures. The proposed reaction mechanism was confirmed based on the DFT calculations.

Practical Pd-catalyzed 2-pyridones were designed to achieve chromeno[2,3-b]pyridine-2-ones. The reaction proceeds through domino nucleophilic addition and decarboxylative arylation, respectively. This methodology offers a moderately efficient approach to construct the bioactive, fused-heterocyclic skeletons via selective C-O bond formation and decarboxylative arylation in a single step with high selectivity and good yields.

In this project, a moderately efficient approach to multisubstituted N-(isoquinolin-1-yl)sulfonamide derivatives was illustrated, utilizing ortho-alkynylbenzaldoximes and zwitterionic ketenimine salts in a tandem reaction catalyzed by silver oxide. The oxophilicity of Ag2O, along with its nature as Lewis acid, pave the way for a smooth [3 + 2] cycloaddition between isoquinoline N-oxides and ketenimine species, which is a key step in this reaction. DFT calculation suggests that 1,3-dipolar cycloaddition of nitrone and ketenimine proceeds through a selective stepwise mechanism.

A novel copper-catalyzed cycloisomerization of unactivated allene-tethered O-propargyl oximes has been developed for the synthesis of hexahydropyrrolo[3,4-b]azepin-5(4H)-ones. This one-pot domino reaction proceeds via a [2,3]-sigmatropic rearrangement, a [3 + 2] cycloaddition, and another [3,3]-sigmatropic rearrangement. The methodology offers a practical and straightforward route for the rapid assembly of both ring components of the fused bicyclic motifs from acyclic precursors by simultaneously forming four new bonds (a C═O, a C═N, and two C-C bonds) in a single step.

A sequential post-transformation of Ugi four-component reaction/nucleophilic substitution was developed for the synthesis of spiro-β-lactam-pyrroloquinolines. This method involves the Ugi-4CR of 2-chloro-3-formyl quinolines

An efficient synthesis of diketopiperazinoindolines through an indium-catalyzed intramolecular 5-exo-dig cyclization of ortho-alkynyl diketopiperazines has been reported. The formation of diketopip...

The silver(I)-catalyzed reaction of ortho-alkynylbenzaldoximes with propargylic alcohols represents a new strategy for the divergent one-pot synthesis of 2-(isoquinolin-1-yl) prop-2-en-1-ones via tandem 6-endo-cyclization, 1,3-dipolar cycloaddition, and intramolecular dehydrative opening of the 2,3-dihydroisoxazole ring. This synthetic protocol tolerates a wide variety of ortho-alkynylbenzaldoximes and propargylic alcohols and affords the corresponding products in excellent yields.

An efficient approach for the synthesis of pyranoquinolines through the indium-catalyzed activation of alkynes is reported. Intramolecular hydroamidation of alkynes can proceed through alkyne activation by indium(III) and then 6-exo-dig cyclization, leading to a fused pyran ring with high selectivity, high atom economy, and good to excellent yields. The cyclization was accomplished through the oxygen, not the nitrogen, of the amide functional group.

An efficient approach for the synthesis of functionalized β-lactams and pyrrolidine-2,5-diones was achieved through a sequential Ugi-4CR/cyclization reaction. Diversity-oriented synthesis, good to high yields, easy workup, and short reaction times are advantages of this procedure.

The Pt/Pd/Fe trimetallic nanoparticle (Pt/Pd/Fe T-NP) was prepared using a water-in-oil microemulsion system of water/AOT/isooctane at room temperature. This nanoparticle (NP) was physically characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray fluorescence (XRF) analyses. The said NP was used as catalyst for hydrodehalogenation (HDH) of halogenated organic compounds (HOCs), and its capability in hydrodechlorination (HDC) of chlorobenzene was compared with Pt/Pd, Pt/Fe, and Pd/Fe bimetallic nanoparticles (B-NPs) synthesized via the same method. The formation of mixed Pt/Pd/Fe ensembles results in an enhanced overall activity and reusability of HDC reaction, compared with Pd/Fe catalyst which acted as the best B-NP. Recycling experiments were examined for HDC of chlorobenzene. To get a maximum conversion of HDC, the reaction parameters like the effect of solvent, amounts of catalyst and ammonium formate were optimiz...

International audience; The compositions and structures of bovine and camel milk proteins are different, which define their functional and biological properties, The aim of this study was to investigate the effects of enzymatic hydrolysis of camel and bovine whey proteins (WPs) on their antioxidant and antimicrobial properties. After enzymatic treatment, both the antioxidant and the antimicrobial activities of bovine and camel WPs were improved. The significantly higher antioxidant activity of camel WPs and their hydrolysates as compared with that of bovine WPs and their hydrolysates may result from the differences in amounts and/or in accessibilities of antioxidant amino acid residues present in their primary structures and from the prevalence of alpha-lactalbumin and Beta-lactoglobulin as proteolytic substrates in camel and bovine whey, respectively. The results of this study reveal differences in antimicrobial and antioxidant activities between WP hydrolysates of bovine and camel milk and the effects of limited proteolysis on these activities