Thermal properties of azidohetarenes without reactive ortho-substituents, obtained by DSC analysis, were compared with the DSC data of ortho-phenyl and ortho-acyl substituted azidohetarenes, which give ring closure reactions either to indoles or to five-membered heterocycles such as isoxazoles. The reaction temperatures and reaction enthalpies give both information to prepare the reaction condi...

We disclose herein a highly enantioselective protocol for the Brønsted acid-catalyzed addition of indoles and phenols to in situ-generated ortho-quinone methides which deliver broadly substituted diarylindolylmethanes and triarylmethanes, respectively, in a one-pot reaction under very mild conditions. A chiral phosphoric acid catalyst has been developed for this process serving to convert the s...

in this study, the conditions for producing invert syrup were optimized and factors such as type of acid citric, hydrochloridric and tartaric (each at two levels), reaction time (1 and 1.5 h) and temperature (70 and 80°c) were studied. the properties of invert syrups which produced by different methods were compared with each other and a standard and optimized method, for inversion reaction, wa...

C2-symmetric vicinal diamines 3b–f, derived from L-tartaric acid, with increasingly bulky terminal ether functionalities were prepared using two distinct sequences. Diamines 3b,c were obtained from the corresponding vicinal diols 4b,c, while diamines 3d–f were generated from dihydroxydiazide 7 via deprotection–reprotection strategies. © 1999 Elsevier Science Ltd. All rights reserved.

The -ethylphenylamine tartaric acid salts 1a-1d were synthesized from R-(+)/S-(-)-ethylphenylamine by reacting with (2S,3S)-(+)/(2R,3R)-(-) dihydrobutanedioic acid. They were used as the catalysts in cyanosilylation of prochiral aldehydes to give the corresponding cyanohydrin trimethylsilyl ethers in moderate conversion at room temperature.

We report here the first systematic study of nickel-catalyzed decarbonylation of aromatic aldehydes under relatively mild conditions. Aldehydes with electron donating groups at para and ortho positions are generally successful with our method. For aldehydes with electron-withdrawing groups, significantly higher yields were achieved for ortho-substituted substrates than para ones, probably due t...

BACKGROUND The present study was conducted to evaluate the effect of different topical agents utilized for prevention of enamel decalcification around orthodontic brackets bonded to bleached and non-bleached enamel. METHODS Human maxillary premolars (n = 120) were divided into two equal groups. Teeth in group I were left without bleaching while those in group II were bleached with Vivastyle g...