Reactions catalyzed by a binuclear copper complex: selective oxidation of alkenes to carbonyls with O2

A binuclear copper complex bearing a simple salicylate ligand catalyses the efficient cleavage of styrenes into ketones and aldehydes with O₂ as the oxidant. The reaction works under an atmosphere of O₂ (balloon) with 0.5 mol% of catalyst and could be performed on a gram scale, providing an alternative to ozonolysis.

Cleavage of a carbon-carbon triple bond via gold-catalyzed cascade cyclization/oxidative cleavage reactions of (Z)-enynols with molecular oxygen

A highly efficient carbon-carbon triple bond cleavage reaction of (Z)-enynols was developed, which offered a new route to highly substituted butenolides. The methodology is realized by a tandem reaction using a single gold(I) catalyst, which could catalyze different reactions of cyclization/oxidative cleavage in the same vessel.

Elusive Forms and Structures of N-Hydroxyphthalimide: The Colorless and Yellow Crystal Forms of N-Hydroxyphthalimide

A comprehensive structural characterization of the colorless and yellow forms of N-hydroxyphthalimide (NHP), the deuterated form (NDP), and the ethoxylated form (ethoxy-NHP) has been carried out using single-crystal X-ray diffraction, FTIR and Raman spectroscopies, and scanning electron microscopy. Both NHP and NDP forms crystallize in the monoclinic space group (P21/c, No. 14). The various forms of NHP differ in the way in which the molecules adjoin one another through their N-hydroxyl groups and how the carbonyls of the isoindole-1,3-dione ring differ through intermolecular hydrogen bonding. Although the hydrogen bonding about the b axis is virtually the same, the isoindole-1,3-dione ring experiences different twists for the two NHP forms. Both the colorless and yellow forms of NHP exhibit strong intermolecular hydrogen bonding between O(3) and H(1). In the yellow form, the N-hydroxyl group is significantly out of the plane (approximately 1.19 degrees ), but the N-hydroxyl group in the colorless form is only approximately 0.06 degrees out of the plane. Both forms of NHP reveal an infinite chain of intermolecular hydrogen-bonded molecules in the direction of the b axis; however, the molecules are ordered differently within the unit cells. The hydrogen-bond geometry for the yellow form of NHP is O(2)-H(1)...O(3), with an angle of 185 degrees , intermolecular distances of O(2)...O(3) = 2.68 A and H(1)...O(3) = 1.70 A, and an intramolecular hydrogen bond of O(1)...H(1) = 1.17 A. The colorless form of NHP shows an intermolecular hydrogen-bond geometry between O(3) and H(1) with a distance of 1.78 A; the O(2)-O(3) distance is 2.71 A. The O(2)-H(1)...O(3) angle is 159 degrees, and the intramolecular distance is O(1)...H(1) = 0.97 A. The N-ethoxy derivative of NHP crystallizes in an orthorhombic space group (Pnma, No. 62) and exhibits no hydrogen bonding, displaying a strong head-to-tail stacking of the planar rings along the needle axis direction.

Visible light-induced highly selective transformation of olefin to ketone by 2,4,6-triphenylpyrylium cation encapsulated within zeolite Y

2,4,6-Triphenylpyrylium cation encapsulated within zeolite Y promotes highly selective transformation of olefins to ketones with molecular oxygen, under visible light (lambda > 400 nm) irradiation at room temperature.

Alkane Oxidation with Molecular Oxygen Using a New Efficient Catalytic System: N-Hydroxyphthalimide (NHPI) Combined with Co(acac)(n)() (n = 2 or 3)

A novel class of catalysts for alkane oxidation with molecular oxygen was examined. N-Hydroxyphthalimide (NHPI) combined with Co(acac)(n)() (n = 2 or 3) was found to be an efficient catalytic system for the aerobic oxidation of cycloalkanes and alkylbenzenes under mild conditions. Cycloalkanes were successfully oxidized with molecular oxygen in the presence of a catalytic amount of NHPI and Co(acac)(2) in acetic acid at 100 degrees C to give the corresponding cycloalkanones and dicarboxylic acids. Alkylbenzenes were also oxidized with dioxygen using this catalytic system. For example, toluene was converted into benzoic acid in excellent yield under these conditions. Ethyl- and butylbenzenes were selectively oxidized at their alpha-positions to form the corresponding ketones, acetophenone, and 1-phenyl-1-butanone, respectively, in good yields. A key intermediate in this oxidation is believed to be the phthalimide N-oxyl radical generated from NHPI and molecular oxygen using a Co(II) species. The isotope effect (k(H)/k(D)) in the oxidation of ethylbenzene and ethylbenzene-d(10) with dioxygen using NHPI/Co(acac)(2) was 3.8.