Hydrogen peroxide urea adduct

Immediately upon addition of the urea-hydrogen peroxide adduct to the solution containing methyltrioxorhenium, a yellow color develops due to formation of the catalytically active rhenium peroxo complexes.3... 

Urea hydrogen peroxide adduct (UHP) was employed in metal-catalysed asymmetric epoxidation [98] and Baeyer-Villiger oxidation [99,100]. Since the presence of urea does not change the course of the reaction, this will not be described here. Conversion of epoxides to halohydrins with elemental... 

UHP = urea-hydrogen peroxide adduct Balicki. R. Kaczmarek, L. Synth. Commun., 1993, 23, 3149... 

For the preparation of [l]benzothieno[3,2- ][l]benzofuran-10,10-dioxide 64, hydrogen peroxide in acetic acid, 3-chloroperoxybenzoic acid, and also the urea-hydrogen peroxide adduct with phthalic anhydride were employed. All three methods provided 64 in excellent yields (88-94%). Monitoring the course of the reaction showed the... 

The starting material (2 mmol) was added to the finely powdered urea-hydrogen peroxide adduct (376 mg, 4 mmol) in a glass test tube, and the reaction mixture was placed in an oil bath at 85 °C. After completion of the reaction, monitored by TLC, the reaction mixture was extracted into ethyl acetate and the combined extracts were washed with water and dried over anhydrous sodium sulfate. The solvent was removed under reduced pressure to afford the crude product, which was purified by chromatography to deliver pure product, as confirmed by the spectral analysis. 

W. M. Adam, C. M. Mitchell, Methyltrioxorhenium(VII)-catalyzed epoxidation of alkenes with the urea/hydrogen peroxide adduct, Angew. Chem. Int. Ed. Engl. 35, 533— 535 (1996). 

Boehlow, T.R., and Spilling, C.D., The regio- and stereo-selective epoxidation of alkenes with methyl trioxorhenium and urea-hydrogen peroxide adduct. Tetrahedron Lett., 37, 2717, 1996. 

As mentioned before (Section 7.2.1), aqueous hydrogen peroxide is an ecofriendly and versatile reagent. Thus, as shown in Scheme 7.8, Katsuki used chiral titanium-salen catalyst 12 for the oxidation of sulfides with hydrogen peroxide or urea-hydrogen peroxide adduct (UHP). Under these mild reaction conditions, chiral sulfoxides were obtained in good yields with high enantioselectivities. 

A convenient methodhas been developed. It involves in using urea-hydrogen peroxide adduct (UHP, H NCONH, H Oj) in presence of catalytic amount of KjCOj in water-acetone at room temperature (Scheme 87). 

The oxo-vanadium(rV) complexes [VOCl2 HOCH2C(pz)3 ] (5) and [VO(acac)2(Hpz)] (7), immobilized on a polydimethyl-siloxane (PDMS) membrane, act as supported catalysts for the cyclohexane oxidation (Scheme 22.2) using benzoyl peroxide (BPO), ferf-butyl hydroperoxide, mCPBA, hydrogen peroxide, or the urea-hydrogen peroxide adduct as oxidants (TONs up to 620) [5b]. The best results were obtained with the less polar mCPBA or BPO on account of the hydrophobic character of the membrane that favors their sorption. 

The transformation of nitriles into amides is a well-known and well-studied reaction that can be carried out under a variety of conditions and generally requires heating, a long reaction time and metal catalysts [40], A simple, mild and efficient method uses urea-hydrogen peroxide adduct (UHP H2NC0NH2 H202) in the presence of a catalytic amount of K2CO3 in water-acetone at room temperature [40, 41]. Some results are reported in Table 6.5. The procedure is efficient for both aromatic and aliphatic nitriles, and other hydrolyzable functionalities are preserved. 

Musumeci, D. and Sica, D. (2002) CHsReOs-catalyzed oxidation of cholesta-5,7-dien-3 3-yl acetate with the urea-hydrogen peroxide adduct under various conditions. Synthesis of the natural epoxy sterol 9a,lla-epoxy-5a-cholest-7-en-3 3,5,6 3-triol. Steroids, 67, 661-668. 

Recently, Katsuki and Saito reported that di-g-oxo titanium complexes of chiral salen ligands serve as efficient catalysts for asymmetric oxidation of various sulfides using H2O2 or the urea-hydrogen peroxide adduct as oxidants [108]. Enantioselectiv-... 

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