- Novel Method for O-Acetylation of Cholesterol, Allobetulin, and Betulin
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Primary and secondary triterpene alcohols were acetylated for the first time using tetraacetylglycoluril (TAGU). Cholesterol, allobetulin, and betulin acetates were obtained in high yields. The acetylation used p-TsOH or TFA in refluxing CHCl3. TFA was found to be an effective acetylation catalyst.
- Arrous, Salah,Boudebouz, Imene,Bakibaev, Abdigali,Hoang, Phuoc,Parunov
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- Efficient Synthesis of Tetraacetylglycoluril in the Presence of Phosphorus-Containing Catalysts
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Abstract: The effect of phosphorus-containing catalysts, namely phosphorous acid, phosphoric acid, diethyl hydrogen phosphite, and 1-hydroxyethane-1,1-diyldiphosphonic acid (HEDP), in the synthesis of tetraacetylglycoluril by acylation of glycoluril with acetic anhydride at 140°C has been studied. The use of 4 equiv of phosphorous or phosphoric acid with respect to glycoluril has been found to be the most appropriate for achieving the maximum yield (95–98%), and specific effect of HEDP leads to N-acetylation–deacetylation of substrates. The positive effect of phosphorus acids on the formation of tetraacetylglycoluril may be related to not only their catalytic action but also the ability to solubilize the substrate.
- Bakibaev,Panshina, S. Yu.,Hoang,Kurgachev,Ukhov,Malkov,Zhumanov
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- 1,6-Dibenzylglycoluril for synthesis of deprotected glycoluril dimer
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1,6-Dibenzylglycoluril is not accessible via classical condensation reaction between substituted urea and glyoxal. In this paper 1,6-dibenzylglycoluril was successfully prepared by alkylation of 1,6-diacetylglycoluril with benzylbromide for the first time. 1,6-Dibenzylglycoluril reacted with formaldehyde to give tetrabenzylglycoluril dimer. Deprotection of this dimer and the previously reported o-xylyleneglycoluril dimer was achieved by dissolving metal reduction, whereas propyleneglycoluril dimer was deprotected by action of potassium persulfate.
- Stancl, Marek,Khan, Muhammad S.A.,Sindelar, Vladimir
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experimental part
p. 8937 - 8941
(2011/12/01)
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- Methodes de preparation de derives nitres et nitroacetyles du glycolurile (I)
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A procedure for preparing nitro and nitroacetyl derivatives of glycoluril is described, starting from tetraacetylglycoluril (TAGU).The method proceeds by nitrodeacetylation and (or) hydrolysis.New compounds have been prepared : mononitrodiacetylglycoluril (MONDAGU), dinitrodiacetylglycoluril (DINDAGU) and mononitroglycoluril (MONGU).A general synthetic scheme is proposed and discussed.Some properties of the new derivatives are presented.
- Boileau, J.,Wimmer, E.,Carail, M.,Gallo, R.
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p. 465 - 469
(2007/10/02)
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