19793-87-4Relevant academic research and scientific papers
Chemoselective Pd-catalyzed oxidation of polyols: Synthetic scope and mechanistic studies
Chung, Kevin,Banik, Steven M.,De Crisci, Antonio G.,Pearson, David M.,Blake, Timothy R.,Olsson, Johan V.,Ingram, Andrew J.,Zare, Richard N.,Waymouth, Robert M.
, p. 7593 - 7602 (2013)
The regio- and chemoselective oxidation of unprotected vicinal polyols with [(neocuproine)Pd(OAc)]2(OTf)2 (1) (neocuproine = 2,9-dimethyl-1,10-phenanthroline) occurs readily under mild reaction conditions to generate α-hydroxy ketones. The oxidation of vicinal diols is both faster and more selective than the oxidation of primary and secondary alcohols; vicinal 1,2-diols are oxidized selectively to hydroxy ketones, whereas primary alcohols are oxidized in preference to secondary alcohols. Oxidative lactonization of 1,5-diols yields cyclic lactones. Catalyst loadings as low as 0.12 mol % in oxidation reactions on a 10 g scale can be used. The exquisite selectivity of this catalyst system is evident in the chemoselective and stereospecific oxidation of the polyol (S,S)-1,2,3,4-tetrahydroxybutane [(S,S)-threitol] to (S)-erythrulose. Mechanistic, kinetic, and theoretical studies revealed that the rate laws for the oxidation of primary and secondary alcohols differ from those of diols. Density functional theory calculations support the conclusion that β-hydride elimination to give hydroxy ketones is product-determining for the oxidation of vicinal diols, whereas for primary and secondary alcohols, pre-equilibria favoring primary alkoxides are product-determining. In situ desorption electrospray ionization mass spectrometry (DESI-MS) revealed several key intermediates in the proposed catalytic cycle.
Efficient oxidation of 1,2-diols into a-hydroxyketones catalyzed by organotin compounds
Maki, Toshihide,Iikawa, Shinya,Mogami, Gen,Harasawa, Hitomi,Matsumura, Yoshihiro,Onomura, Osamu
experimental part, p. 5364 - 5370 (2009/12/22)
Electrochemical oxidation of 1,2-diols with a catalytic amount of an organotin compound and a bromide ion as mediators has been developed. Various cyclic and acyclic 1,2-diols were oxidized into the corresponding α-hydroxyketones in good to excellent yields without C-C bond cleavage. Also, oxidation with the use of chemical oxidants was accomplished in the presence of a catalytic amount of an organotin compound. These reactions could discriminate 1,2-diols from isolated hydoxyl groups or 1,3-diols. In the case of a conformationally restricted cyclic 1,2-diol, the axial hydroxyl group was oxidized exclusively. Mono-, di-, and trialkylated tin compounds were examined as mediators and dialkylated tin compounds showed higher catalytic activity than mono- and trisubstituted ones. Me2SnCl2 was found to be the most suitable mediator for the selective oxidation..
Glycomimetic replacements for hexoses and N-acetyl hexosamines
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Page/Page column 28, (2008/12/06)
Compounds and methods are provided for obtaining oligosaccharide mimics. More specifically, compounds and methods are described wherein oligosaccharide mimics are obtained by incorporating or substituting in a cyclohexane derivative.
Methods of use of glycomimetics with replacements for hexoses and n-acetyl hexosamines
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Page/Page column 35; sheet 7, (2008/12/08)
Methods are provided for using a compound to treat, for example, endothelial dysfunction including vascular abnormalities. More specifically, methods are described for using an oligosaccharide compound or glycomimetic compound wherein a cyclohexane derivative is incorporated in either.
Diastereoselective inter- and intramolecular pinacol coupling of aldehydes promoted by monomeric titanocene(III) complex Cp2TiPh
Yamamoto,Hattori,Miwa,Nakagai,Kubota,Yamamoto,Okamoto,Itoh
, p. 3865 - 3870 (2007/10/03)
A monomeric titanocene(III) derivative, Cp2TiPh, effectively promoted the pinacol coupling of both an aromatic aldehyde, benzaldehyde, and an aliphatic aldehyde, 3-phenylpropionaldehyde. The same reactive complex was successfully generated by a catalytic amount of a precursor, Cp2Ti(Ph)Cl, and its stoichiometric amount of Zn. The Cp2TiPh-catalyzed pinacol coupling of benzaldehyde derivatives and aliphatic aldehydes afforded the corresponding 1,2-diols in high yields with moderate to good threo-selectivity. On the other hand, Cp2TiPh-catalyzed pinacol-cyclization of dials gave cyclic 1,2-diols with excellent diastereoselectivity. The extension of this protocol to chiral dials demonstrated that the phenyltitanium complex catalytically transmitted an axial chirality or a central, chirality of the starting dials to the central chirality of the resultant 1,2-diols.
Highly trans-selective intramolecular pinacol coupling of dials catalyzed by bulky Cp2TiPh
Yamamoto, Yoshihiko,Hattori, Reiko,Itoh, Kenji
, p. 825 - 826 (2007/10/03)
Cp2Ti(Ph)Cl in the presence of Me3SiCl and Zn provides an effective pinacol coupling catalyst for aromatic and aliphatic aldehydes.
On the dihydroxylation of cyclic allylic alcohols
Donohoe, Timothy J.,Garg, Rina,Moore, Peter R.
, p. 3407 - 3410 (2007/10/03)
The preparation and dihydroxylation (OsO4) of a series of conformationally constrained allylic alcohols is described. By using dichloromethane as solvent, the selectivity that favours the anti triol is substantially reduced by hydrogen-bonding
