21676-89-1

CO2utilization is an attractive aspect as it allows the direct conversion of CO2into valuable chemicals. In this regard, direct incorporation of CO2into the C-H bond of heteroaromatic compounds is important due to the ubiquitous structural motifs of the heteroaromatic carboxylic acids. Herein, we report the Ag-catalyzed C-H carboxylation of thiophene derivatives. This new catalytic system involving a phosphine ligand and lithiumtert-butoxide enables the direct carboxylation of thiophenes under mild reaction conditions. Experimental studies revealed that the use oftert-butyl alkoxide is critical for the exergonic formation of an arylsilver intermediate, and the results were further supported by density functional theory calculations.

Gomberg-Bachmann-Hey reactions were carried out in the presence of copper as a catalyst and gave rise to biaryls or heterobiaryls in good yields and in mild reaction conditions. A computational study of some key points of the reaction was performed. The results are coherent with the experimental data and confirm some aspects of the mechanism. The reaction free energies for the reduction in benzene by CuI of a set of 40 (hetero)arenediazonium tetrafluoroborates were calculated. Both the experiments and the calculations showed that in the coupling with substituted solvents (toluene, bromobenzene, nitrobenzene and anisole) the binding to the ortho position was always favoured.

A visible-light photocatalytic aerobic oxidative lactonization of arene C(sp 2)-H bonds proceeds in the presence of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and tert -butyl nitrite (TBN). Under the optimized conditions, a range of 2-arylbenzoic acids is converted into the corresponding benzocoumarin derivatives in moderate to excellent yields. This method is characterized by its atom economy, mild reaction conditions, the use of a green oxidant and metal-free catalysis.

Arenediazonium o-benzenedisulfonimides have been used as efficient electrophilic partners in Au(I) catalysed Suzuki coupling reactions. The synthetic protocol is general, easy and produced either biaryls or heteroaryl arenes in good yields (51 positive examples, average yield 80%). o-Benzenedisulfonimide was recovered at the end of the reactions and was reused to prepare the starting salts for further reactions. Mechanistic insights suggest that the o-benzenedisulfonimide anion act as an electron transfer agent and promotes a catalytic cycle which does not require the presence of photocatalysts or external oxidants.

Ruthenium ligated to tricyclohexylphosphine or di-tert-butylbipyridine catalyzes the arylation of carboxylic acids with diverse aryl halides (iodide, bromide, and triflate; aryl and heteroaryl). In addition, arylations with 2-iodophenol formed benzochromenones, carboxylate was shown to be a stronger donor than an amide, and the arylation of a pyridine carboxylate was demonstrated. Stoichiometric studies demonstrated that the added ligand is required for reaction with the electrophile but not the C-H bond.

Silver-catalyzed C(sp2)-H functionalization/C-O cyclization has been developed. The scalable reaction proceeds at room temperature in an open flask. The present method exhibits good functional-group compatibility because of the mild reaction conditions. Using a AgNO3 catalyst and a (NH4)2S2O8 oxidant in CH2Cl2/H2O solvent, various lactones are obtained in good to excellent yields. A kinetic isotope effect (KIE) study indicates that the reaction may occur via a radical process.

Herein, we describe the synthesis and pharmacological profiles of novel quinuclidinyl heteroarylcarbamate derivatives. Among them, the quinuclidin-4-yl thiazolylcarbamate derivative ASP9133 was identified as a promising long-acting muscarinic antagonist (LAMA) showing more selective inhibition of bronchoconstriction against salivation and more rapid onset of action in a rat model than tiotropium bromide.

Aryl-heteroaryl and heteroaryl-heteroaryl compounds are obtained through the Suzuki-Miyaura cross-coupling reactions between diazonium salts and potassium trifluoroborates using PdCl2(CH3CN)2 as the catalyst in water and in the absence of any additive, ligand or base. In addition, the same mild catalytic system is effective for the Matsuda-Heck reaction between several monoolefins with aryldiazonium salts.

A concise and efficient approach to a series of chromen-4-ones with fused thiophene ring has been developed using the Suzuki-Miyaura reaction of bromothiophene-2- and 3-carboxylates with 2-methoxyboronic acids and subsequent cyclization of prepared alkyl (2-methoxy)aryl thiophene-2- and 3-carboxylates under the action of BBr3/KOtBu. Starting bromothiophenes are easily obtained from corresponding commercially available aminothiophenes by diazotization/bromination reaction.

The palladium-catalyzed Matsuda-Heck and Suzuki-Miyaura cross-couplings of 2-methoxycarbonylthiophene-3-diazonium tetrafluoroborate 1 were performed to synthesize a series of thiophene derivatives functionalized in the β-position. Good to excellent yields of the cross-coupling products were obtained using palladium acetate [Pd(OAc)2], a ligandless palladium catalyst, without a base, at room temperature, under aerobic conditions and with short reaction times. A diazotization and cross-coupling sequence can also be performed in a one-pot process avoiding the isolation of the thiophenediazonium salt derivative. In addition, 2-methoxycarbonylbenzo[b]thiophene-3-diazonium tetrafluoroborate 8 was also efficiently arylated by applying the same Suzuki-Miyaura optimized reaction conditions. Copyright

New thiophene compounds and a new process for the manufacture of thiophene compounds by dehydrogenating dihydrothiophene with certain halogen compounds. The products are starting materials for the manufacture of pharmaceuticals, dyes and plant protection agents and, in particular, for the manufacture of additives to foodstuffs, feeds, beverages and pharmaceuticals.