84895-18-1Relevant articles and documents
Controlling Selectivity in Alkene Oxidation: Anion Driven Epoxidation or Dihydroxylation Catalysed by [Iron(III)(Pyridine-Containing Ligand)] Complexes
Tseberlidis, Giorgio,Demonti, Luca,Pirovano, Valentina,Scavini, Marco,Cappelli, Serena,Rizzato, Silvia,Vicente, Rubén,Caselli, Alessandro
, p. 4907 - 4915 (2019/08/30)
A highly reactive and selective catalytic system comprising Fe(III) and macrocyclic pyridine-containing ligands (Pc-L) for alkene oxidation by using hydrogen peroxide is reported herein. Four new stable iron(III) complexes have been isolated and characterized. Importantly, depending on the anion of the iron(III) metal complex employed as catalyst, a completely reversed selectivity was observed. When X=OTf, a selective dihydroxylation reaction took place. On the other hand, employing X=Cl resulted in the epoxide as the major product. The reaction proved to be quite general, tolerating aromatic and aliphatic alkenes as well as internal or terminal double bonds and both epoxides and diol products were obtained in good yields with good to excellent selectivities (up to 93 % isolated yield and d.r.=99 : 1). The catalytic system proved its robustness by performing several catalytic cycles, without observing catalyst deactivation. The use of acetone as a solvent and hydrogen peroxide as terminal oxidant renders this catalytic system appealing.
Mesoporous aluminosilicate promoted protection and deprotection of carbonyl compounds
Robinson, Mathew W.C.,Graham, Andrew E.
, p. 4727 - 4731 (2008/02/07)
Mesoporous aluminosilicates are efficient heterogeneous catalysts for both the formation and hydrolysis of a range of acetals under mild conditions and in short reaction times.
Chromyl Complexes in the Direct Epoxidation of Alkenes
Miyaura, N.,Kochi, J. K.
, p. 2368 - 2378 (2007/10/02)
Alkenes such as (E)- and (Z)-β-methylstyrene are converted stereospecifically by dinitratodioxochromium(VI), or chromyl nitrate, to the corresponding epoxide with high selectivities in aprotic media under rather mild conditions.The presence of the cosolvents, N,N-dimethylformamide (DMF), acetone, pyridine, etc., is critical for effective epoxidation with this reagent.In DMF and pyridine, the epoxide remains generally intact but in acetone it is transformed to the corresponding alkene ketal which can also be isolated in high yields.The rates of oxidation are evaluated by the competition method, and the relative reactivities of various alkenes toward chromyl nitrate are found to generally parallel those previously determined for other chromyl reagents such as chromic acid, chromyl acetate, and chromyl chloride.Under optimum conditions for epoxidation, chromyl nitrate effects exclusive oxidation of 1,2-diphenylethanol to deoxybenzoin, which is uncontaminated by the usual cleavage products benzaldehyde and benzyl alcohol.Since the latter is known to derive from chromium(IV) intermediates, we conclude that the active species in chromyl epoxidation is oxochromium(V) formed in situ by the prior one-electron oxidation of solvent.The latter is in accord with the efficient transfer of the oxygen atom from macrocyclic oxochromium(V) species previously observed by Grovers and co-workers.The ESR spectra of the transient chromium(V) intermediates derived from chromyl nitrate and chromyl acetate by reduction with cosolvent are reported.
