626-86-8Relevant articles and documents
Oxidation of cyclohexanone and/or cyclohexanol catalyzed by Dawson-type polyoxometalates using hydrogen peroxide
Dermeche, Leila,Idrissou, Yasmina,Mazari, Tassadit,Moudjahed, Mohammed,Rabia, Cherifa
, (2022/03/07)
The oxidation of cyclohexanone, cyclohexanol or cyclohexanone/cyclohexanol mixture using as catalyst, Dawson-type polyoxometalates (POMs) of formula, α- and β-K6P2W18O62, α-K6P2Mo6W12O62 and α1-K7P2Mo5VW12O62 and hydrogen peroxide, carried out at 90 °C with a reaction time of 20 h, led to a high number of mono- and di-acids which were identified by GC-MS. Levulinic, 6-hydroxyhexanoic, adipic, glutaric and succinic acids, major products were evaluated by HPLC. Regardless of the substrate nature, all POMs exhibited high catalytic activity with 94–99% of conversion, whereas the formation of the different products is sensitively related to both the composition and symmetry of the POMs and the substrate nature. The main products are adipic acid in the presence of α-K6P2Mo6W12O62 and α1-K7P2Mo5VW12O62, levulinic acid in the presence of α1-K7P2Mo5VW12O62 and β-K6P2W18O62 and 6-hydroxyhexanoic acid in the presence of α- and β-K6P2W18O62. Graphical abstract: High catalytic activity was observed with?α- and?β-K6P2W18O62, α-K6P2Mo6W12O62 and α1-K7P2Mo5VW12O62 Dawson-type for the oxidation of cyclohexanone, cyclohexanol or cyclohexanone/cyclohexanol mixture, in the hydrogen peroxide presence, to several oxygenated products. Adipic, levulinic and 6-hydroxyhexanoic acids are the main products. The peroxo- species formed in situ could be the active sites.[Figure not available: see fulltext.]
Carboxylation of Aromatic and Aliphatic Bromides and Triflates with CO2 by Dual Visible-Light–Nickel Catalysis
Meng, Qing-Yuan,Wang, Shun,K?nig, Burkhard
supporting information, p. 13426 - 13430 (2017/10/07)
We report the efficient carboxylation of bromides and triflates with K2CO3 as the source of CO2 in the presence of an organic photocatalyst in combination with a nickel complex under visible light irradiation at room temperature. The reaction is compatible with a variety of functional groups and has been successfully applied to the synthesis and derivatization of biologically active molecules. In particular, the carboxylation of unactivated cyclic alkyl bromides proceeded well with our protocol, thus extending the scope of this transformation. Spectroscopic and spectroelectrochemical investigations indicated the generation of a Ni0 species as a catalytic reactive intermediate.
Mild Amide-Cleavage Reaction Mediated by Electrophilic Benzylation
Yamada, Kohei,Karuo, Yukiko,Tsukada, Yuichi,Kunishima, Munetaka
supporting information, p. 14042 - 14047 (2016/09/21)
An extremely mild method for amide-cleavage by using the triazine-based benzylating reagent 4-(4,6-diphenoxy-1,3,5-triazin-2-yl)-4-benzylmorpholinium trifluoromethanesulfonate (DPT-BM), which spontaneously releases benzyl cation species when being dissolved at room temperature, has been developed. O-Benzylation of the amide with DPT-BM and the subsequent hydrolysis of the resulting intermediate benzyl imidate salt afford the corresponding amine and benzyl ester, which can be converted by hydrogenolysis into a carboxylic acid under neutral conditions. O-Benzylation proceeds depending on both steric and electronic factors around the amide group. Thus, some amides have been selectively cleaved over other amides. Furthermore, intramolecular chemoselective cleavage of an amide group in the presence of an ester group was achieved. Such selective hydrolytic reactions cannot be performed with Meerwein reagents as well as under acidic or basic hydrolytic conditions.