β-cyclodextrin sulfuric acid as a green lewis acid catalyst has been applied for the preparation of bis(indolyl)methanes, tris(indolyl)methanes and 3,3'-diindolyloxindole derivatives by the condensation of indoles with various carbonyl compounds in aqueous media with high to excellent yields.

The three-dimensional sponge-like mesoporous material TUD-1 is straightforward to prepare. Its synthesis can readily be modified to introduce metals into the framework of TUD-1, imparting many different catalytic activities. M-TUD-1 catalysts have proven to be very active, unlimited by diffusion and very stable. By combining two metals into one TUD-1 catalyst, synergy between Lewis and Brønsted...

the surface of sba-15 was modified by diphenylphosphine; then, it was treated with butane sultone and sulfuric acid to obtain brønsted acid ho3s-phosphonium based ionic liquid functionalized sba-15 with hso4- as a counteranion. it efficiently catalyzed synthesis of pyrano[3,2-c]chromenone derivatives through the reaction of 4-hydroxycoumarin and chalcones at 60 °c in water/ethanol. good yields,...

Research results about the influence of BEA zeolite preliminary dealumination on acid–base characteristics and catalytic performance 1% Zn-BEA compositions in propane dehydrogenation with CO2 are presented. The catalyst samples, prepared through a two-step post-synthesis procedure involving partial or complete specimen followed by introduction Zn2+ cations into T-positions framework, were chara...

Enantioselective control of the chirality of a tertiary a-carbon in the products of a Nazarov cyclization of enones is challenging because the reaction involves an enantioselective proton transfer process. We herein report the use of cooperative catalysis using Lewis acids and chiral Brønsted acids to control the stereochemistry of the tertiary a-carbon in the products of this reaction. Specifi...

The approach using pyrrolidine enamine as substrate has been studied for this synthesis, and an important catalyst structural feature has been developed. After survey of pyrrolidine-based Brønsted acid catalyst, tetrazole catalyst (3f) was found to be optimal in synthesis of aminooxy carbonyl compounds in high yields, with complete enantioselectivity not only for aldehydes but also for ketones.

A zirconium modified MCM-48 mesoporous material was synthesized by surfactant-templated method. Surface grafting Zr-MCM-48 with tungstophosphoric acid led to a great enhancement of both the number of the Brønsted acid sites and acidity strength in comparison with the bare support. At 100 ̊C, the 30 wt% H3PW12O40/Zr-MCM-48 contained 174 mol/g Brønsted acid sites which were 21.7 times greater tha...

The catalytic purification of automobile exhaust gases (CO, NOx and hydrocarbons) is one of the most practiced conversion processes used to lower the emissions and to reduce the air pollution. Nevertheless, the good performance of exhaust gas purification catalysts often requires the high consumption of noble metals such as platinum. Here we report that the Brønsted acid sites on the external s...

In this study we have developed an efficient synthesis of 1,2-dihydroquinoline and dihydrobenzo[b]azepine derivatives involving the iron(III) chloride intramolecular alkyne-carbonyl metathesis reaction for the first time. Various functionalized 1,2-dihydroquinolines and dihydrobenzo[b]azepines were prepared from easily accessible substrates in the presence of environmentally friendly and inexpe...

Pyrido[2,3-d]pyrimidine derivatives were synthesized regioselectivly in good to high yields by one-pot three-component condensation of 6-amino-2-(methylthio)pyrimidin-4(3H)-one, aromatic aldehydes and ethylcyanoacetate or meldrum's acid using 1,2-dimethyl-N-butanesulfonic acid imidazolium hydrogen sulfate ([DMBSI]HSO4) Brønsted-acidic ionic liquid as catalyst. Solvent-free mild reaction conditi...