- Stannous chloride as a low toxicity and extremely cheap catalyst for regio-/site-selective acylation with unusually broad substrate scope
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This work reports stannous chloride (SnCl2)-catalyzed regio-/site-selective acylation with unusually broad substrate scope. In addition to 1,2- and 1,3-diols and glycosides containing cis-vicinal diol, the substrate scope also includes glycosides without cis-vicinal diol. For such a substrate scope, usually, only methods using stoichiometric amounts of organotin reagents can lead to the same protection pattern with high selectivities and highly isolated yields (84-97% in most cases). Therefore, SnCl2, as a low toxicity and extremely cheap reagent, should be the best catalyst for regio-/site-selective acylation compared with any previously reported reagents. This journal is
- Dong, Hai,Feng, Guang-Jing,Luo, Tao,Lv, Jian,Yu, Jian-Cheng
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supporting information
p. 6936 - 6942
(2020/11/09)
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- Lead-Catalyzed Aqueous Benzoylation of Carbohydrates with an Acyl Phosphate Ester
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Biochemical systems utilize adenylates of amino acids to aminoacylate the 3′-terminal diols of tRNAs. The reactive acyl group of the biological acylation agent is a subset of the general class of acyl phosphate monoesters. Those compounds are relatively stable in aqueous solutions, and their alkyl esters are conveniently prepared. It has previously been shown that biomimetic reactions of acyl phosphate monoesters with diols and carbohydrates are promoted by lanthanide salts. However, they also promote hydrolysis of acyl phosphate reagents, and the overall yields are modest. An assessment of the catalytic potential of alternative Lewis acids reveals that lead ions may be more effective as catalysts than lanthanides. Treatment of carbohydrates with benzoyl methyl phosphate (BMP) and triethylamine in water with added lead nitrate produces monobenzoyl esters in up to 75% yield. This provides a water-compatible pathway for novel patterns of benzoylation of polyhydroxylic compounds.
- Li, Yuyang,Kluger, Ronald
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p. 7360 - 7365
(2018/07/29)
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- Regioselective benzoylation of diols and carbohydrates by catalytic amounts of organobase
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A novel metal-free organobase-catalyzed regioselective benzoylation of diols and carbohydrates has been developed. Treatment of diol and carbohydrate substrates with 1.1 equiv. of 1-benzoylimidazole and 0.2 equiv. of 1,8-diazabicyclo[5.4.0]undec-7-ene (DB
- Lu, Yuchao,Hou, Chenxi,Ren, Jingli,Xin, Xiaoting,Xu, Hengfu,Pei, Yuxin,Dong, Hai,Pei, Zhichao
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- Selectivity switch in the catalytic functionalization of nonprotected carbohydrates: Selective synthesis in the presence of anomeric and structurally similar carbohydrates under mild conditions
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A catalytic process for the chemo- and regioselective functionalization of nonprotected carbohydrates has been developed. This novel process allows selective thiocarbonylation, acylation, and sulfonylation of a particular hydroxy group in a particular carbohydrate in the simultaneous presence of structurally similar carbohydrates such as anomers. In addition, the chemoselectivity can be switched by regulating only the length of the alkyl chain in the organotin catalyst.
- Muramatsu, Wataru,Takemoto, Yuki
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p. 2336 - 2345
(2013/05/08)
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- Regioselective benzoylation of glycopyranosides by benzoic anhydride in the presence of Cu(CF3COO)2
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Benzoylation of methyl and benzyl glycopyranosides by benzoic anhydride in acetonitrile in the presence of copper(II) trifluoroacetate as a promoter has given monobenzoates with a good yield and high regioselectivity. The composition of monobenzoates depended both on a configuration of hydroxyl groups and on a configuration of aglycone. The simple syntheses of the monobenzoates of some glycosides are offered.
- Evtushenko, Evgeny V.
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p. 111 - 119
(2012/11/07)
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- Regioselective protection of sugars catalyzed by dimethyltin dichloride
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(Chemical Equation Presented) The first catalytic process for protection of hydroxyl groups in sugars has been developed. Highly regioselective protection was accomplished along with high chemical yield. The regioselectivity of the benzoylation was realiz
- Demizu, Yosuke,Kubo, Yuki,Miyoshi, Hiroko,Maki, Toshihide,Matsumura, Yoshihiro,Moriyama, Noriaki,Onomura, Osamu
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supporting information; experimental part
p. 5075 - 5077
(2009/05/07)
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- Chelation-controlled regioselectivity in the lanthanum-promoted monobenzoylation of monosaccharides in water
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Monosaccharides are selectively converted to monobenzoates in a base-catalyzed reaction with benzoyl methyl phosphate (BzMP) and a lanthanum salt in water. Yields are reported in terms of formation of the ester, which competes with hydrolysis of BzMP, to
- Gray, Ian James,Kluger, Ronald
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p. 1998 - 2002
(2008/02/10)
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- Regioselective Monoacylation of Some Glycopyranosides via Cyclic Tin Intermediates
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Selective mono-benzoylation of some pento- and hexo-pyranosides (Me β-L-Ara, Ph α-L-Ara, Me α-D-Xyl, Me β-D-Xyl, Me α-D-Glc, Me-β-D-Glc, Me α-D-Gal, Me β-D-Gal, and Me α-D-Man) by using Bu2SnO was examined in comparaison with the results of the (Bu3Sn)2O method and direct benzoylation.The Bu2SnO method is particularly useful in that it selectively activates an equatorial hydroxyl group wich bears an oxygenated function (OH or OMe) in a cis relationship at an adjacent position, even in the presence of a more reactive primary OH group.The various mono- and di-O-benzoyl derivatives prepared in this work were unambiguously identified by analysis of their 13C-nuclear magnetic resonance spectra.
- Tsuda, Yoshisuke,Haque, Md. Ekramul,Yoshimoto, Kimihiro
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p. 1612 - 1624
(2007/10/02)
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