59871-40-8Relevant articles and documents
Reactivity of TpMe2-supported yttrium alkyl complexes toward aromatic n-heterocycles: Ring-opening or C=C bond formation directed by C-H activation
Yi, Weiyin,Zhang, Jie,Huang, Shujian,Weng, Linhong,Zhou, Xigeng
, p. 867 - 876 (2014)
Unusual chemical transformations such as three-component combination and ring-opening of N-heterocycles or formation of a carbon-carbon double bond through multiple C-H activation were observed in the reactions of Tp Me2-supported yttrium alkyl complexes with aromatic N-heterocycles. The scorpionate-anchored yttrium dialkyl complex [TpMe2Y(CH 2Ph)2(THF)] reacted with 1-methylimidazole in 1:2 molar ratio to give a rare hexanuclear 24-membered rare-earth metallomacrocyclic compound [TpMe2Y(μ-N,C-Im)(η2-N,C-Im)]6 (1; Im=1-methylimidazolyl) through two kinds of C-H activations at the C2- and C5-positions of the imidazole ring. However, [TpMe2Y(CH 2Ph)2(THF)] reacted with two equivalents of 1-methylbenzimidazole to afford a C-C coupling/ring-opening/C-C coupling product [TpMe2Y{η3-(N,N,N)-N(CH3)C 6H4NHCH=C(Ph)CN(CH3)C6H 4NH}] (2). Further investigations indicated that [Tp Me2Y(CH2Ph)2(THF)] reacted with benzothiazole in 1:1 or 1:2 molar ratio to produce a C-C coupling/ring-opening product {(TpMe2)Y[μ-η2:η1-SC 6H4N(CH=CHPh)](THF)}2 (3). Moreover, the mixed TpMe2/Cp yttrium monoalkyl complex [(TpMe2)CpYCH 2Ph(THF)] reacted with two equivalents of 1-methylimidazole in THF at room temperature to afford a trinuclear yttrium complex [Tp Me2CpY(μ-N,C-Im)]3 (5), whereas when the above reaction was carried out at 55 °C for two days, two structurally characterized metal complexes [TpMe2Y(Im-TpMe2)] (7; Im-Tp Me2=1-methyl-imidazolyl-TpMe2) and [Cp3Y(HIm)] (8; HIm=1-methylimidazole) were obtained in 26 and 17 % isolated yields, respectively, accompanied by some unidentified materials. The formation of 7 reveals an uncommon example of construction of a C=C bond through multiple C-H activations. Copyright
Reactions of 2-carbonyl- And 2-hydroxy(or methoxy)alkylsubstituted benzimidazoles with arenes in the superacid CF3SO3H. NMR and DFT studies of dicationic electrophilic species
Ryabukhin, Dmitry S.,Turdakov, Alexey N.,Soldatova, Natalia S.,Kompanets, Mikhail O.,Ivanov, Alexander Yu.,Boyarskaya, Irina A.,Vasilyev, Aleksander V.
supporting information, p. 1962 - 1973 (2019/09/03)
Reactions of 2-carbonyl- and 2-hydroxy(or methoxy)alkylbenzimidazoles with arenes in the Br?nsted superacid TfOH resulted in the formation of the corresponding Friedel-Crafts reaction products, 2-diarylmethyl and 2-arylmethyl-substituted benzimidazoles, in yields up to 90%. The reaction intermediates, protonated species derived from starting benzimidazoles in TfOH, were thoroughly studied by means of NMR and DFT calculations and plausible reaction mechanisms are discussed.
A general approach to substituted benzimidazoles and benzoxazoles via heterogeneous palladium-catalyzed hydrogen-transfer with primary amines
Pizzetti, Marianna,De Luca, Elisa,Petricci, Elena,Porcheddu, Andrea,Taddei, Maurizio
supporting information, p. 2453 - 2464 (2013/01/14)
The synthesis of benzimidazoles starting from o-phenylenediamines and amines in the presence of palladium on charcoal as catalyst is reported. Under microwave dielectric heating it is possible to use a tertiary, a secondary, and even a primary amine as the substrate for a palladium-mediated process to get 2-substituted or 1,2-disubstituted benzimidazoles, depending on the nature of the o-phenylenediamine employed. Primary amines are the most suitable reagents for the atom economy of the overall process that resulted to be general as several different substituted benzimidazoles were obtained in good yield. Benzoxazoles can be also prepared starting from primary amines and o-aminophenol. The reaction is also highly selective as no (poly)-alkylated phenylenediamines or cross-contaminated benzimidazoles are obtained starting from N-monoalkylphenylenediamines. This behavior was interpreted as a scarce aptitude to dehydrogenation of the methylene bonded to the aromatic NH of N-alkylarylamines. The experiments carried out consent to draw an almost complete picture of the reaction pathways occurring during the process. The catalyst can be recycled several times and, although far from optimal performances, catalyst TON=90 is encouraging for further large-scale optimization protocols. In addition, the palladium on charcoal-catalyzed microwave-assisted reaction of o-phenylenediamine gives de-alkylation of tertiary amines and transformation into the secondary ones. Copyright
