Transition-metal-free radical difluorobenzylation/cyclization of unactivated alkenes: access to ArCF2-substituted ring-fused quinazolinones.

A mild and efficient transition-metal-free radical difluorobenzylation/cyclization of unactivated alkenes toward the synthesis of difluorobenzylated polycyclic quinazolinone derivatives with easily accessible α,α-difluoroarylacetic acids has been developed. This transformation has the advantages of wide functional group compatibility, a broad substrate scope, and operational simplicity. This methodology provided a highly attractive access to pharmaceutically valuable ArCF2-containing polycyclic quinazolinones.

Transition-metal catalyzed oxidative spirocyclization of N-aryl alkynamides with methylarenes under microwave irradiation.

A practical synthetic route to construct a variety of 3-benzyl spiro[4,5]trienones was developed via transition-metal Cu/Ag-catalyzed oxidative ipso-annulation of activated alkynes with unactivated toluenes using TBPB as an oxidant under microwave irradiation. This method allows the formation of two carbon-carbon bonds and one carbon-oxygen bond in a single reaction through a sequence of C-H oxidative coupling, ipso-carbocyclization and dearomatization. The advantages of this protocol are its operational simplicity and broad substrate scope, and the ability to afford the desired products in moderate to good yields.

Silver-catalyzed direct C-H oxidative carbamoylation of quinolines with oxamic acids.

A silver-catalyzed efficient and direct C-H carbamoylation of quinolines with oxamic acids to access carbamoylated quinolines has been developed through oxidative decarboxylation reaction. The reaction proceeds smoothly over a broad range of substrates with excellent functional group tolerance and excellent yields under mild conditions.

Silver catalysed decarboxylative alkylation and acylation of pyrimidines in aqueous media.

Decarboxylative alkylation or acylation reactions of simple pyrimidines have been developed in aqueous media. Using aliphatic carboxylic acids or 2-oxocarboxylic acids and pyrimidines as substrates and silver as the catalyst, the 4-substituted alkyl or acyl pyrimidines were isolated in moderate to good yields.

Silver-catalyzed radical tandem cyclization: an approach to direct synthesis of 3-acyl-4-arylquinolin-2(1H)-ones.

A silver-catalyzed efficient and practical synthesis of 3-acyl-4-arylquinolin-2(1H)-ones or 3-acyl-4-aryldihydroquinolin-2(1H)-ones through intermolecular radical addition/cyclization in aqueous solution is reported. This method provides a novel, highly efficient, and straightforward route to substituted quinolin-2-ones or 3,4-dihydroquinolin-2-ones in one step. A possible mechanism for the formation of quinolin-2-ones is proposed.

Selectfluor-mediated tandem cyclization of enaminones with diselenides toward the synthesis of 3-selenylated chromones.

A practical and metal-free approach for the regioselective selenation of chromones employing Selectfluor reagent under mild conditions is described. The developed method is suitable for a wide substrate scope and affords 3-selenylated chromones in good to excellent yield with high selectivity. An ionic mechanism is proposed for this transformation. Furthermore, the application of potassium thiocyanate with enaminones for the synthesis of thiocyano chromones in this transformation is also successful.

[Study on the interaction of L-cysteine dipeptide with DNA].

In the present paper the interaction mechanism and mode of biologically active cysteine dipeptide (Cys-Cys) with DNA was studied by UV-Vis spectrophotometry and fluorescence spectroscopy using ethidium bromide as a fluorescence probe. The results showed that in the buffer solution of Tris-HCl (pH 7.20), at low concentration of Cys-Cys, the ultraviolet spectrum of DNA-Cys-Cys system produced hypochromic effect with increasing the concentration of Cys-Cys. When the concentration of Cys-Cys increased to some high extent, the ultraviolet spectrum of DNA-Cys-Cys system produced hyperchromic effect. Salt-effect experiment showed that the interaction is liable to be affected by the ionic strengths, suggesting the existence of electrostatic binding between Cys-Cys and DNA. The fluorescence of EB-DNA had quenching effect with increasing the concentration of Cys-Cys, and the Stern-Volmer equation indicated that the quenching process was a static one. According to the Lineweaver-Burk equation the binding constant was determined to be 1.640 x 10(4) L x mol(-1). From the above results it can be concluded that the interaction mode of Cys-Cys with DNA was mainly electrostatic binding. These findings could contribute to further investigation on the mechanism of oligopeptides interaction with DNA.

3-(1,3-Benzodioxol-5-yl)-1-phenyl-2,3-dihydro-1H-naphtho[1,2-e][1,3]oxazine.

In the title compound, C(25)H(19)NO(3), the oxazine ring displays a half-chair conformation. The fused benzene ring is nearly parallel to the naphthyl ring system, the dihedral angle between this benzene ring and the naphthyl system being 8.52 (11)°. The imino group is not involved in hydrogen bonding in the crystal structure.

Silver-catalyzed radical tandem cyclization for the synthesis of 3,4-disubstituted dihydroquinolin-2(1H)-ones.

A silver-catalyzed tandem decarboxylative radical addition/cyclization of N-arylcinnamamides with aliphatic carboxylic acids is reported. This method affords a novel and straightforward route to various 3,4-disubstituted dihydroquinolin-2(1H)-ones in aqueous solution.

nBu4NI-catalyzed direct synthesis of α-ketoamides from aryl methyl ketones with dialkylformamides in water using TBHP as oxidant.

A novel and easy practical direct synthesis of α-ketoamides has been developed without metals in water. This procedure was catalyzed by nBu(4)NI using TBHP as oxidant from simple substrates, aryl methyl ketones and dialkylformamides.