- Regio/site-selective alkylation of substrates containing a: Cis -, 1,2- or 1,3-diol with ferric chloride and dipivaloylmethane as the catalytic system
-
In this study, we reported the regio/site-selective alkylation of substrates containing a cis-, 1,2- or 1,3-diol with FeCl3 as a key catalyst. A catalytic system consisting of FeCl3 (0.01-0.1 equiv.) and dipivaloylmethane (FeCl3/dipivaloylmethane = 1/2) was used to catalyze the alkylation in the presence of a base. The produced selectivities and isolated yields were similar to those obtained by methods using the same amount of FeL3 (L = acylacetone ligand) as the catalyst in most cases. The previously reported FeL3 catalysts for alkylation are not commercially available and have to be synthesized prior to use. In contrast, FeCl3 and dipivaloylmethane (Hdipm) are very common and inexpensive nontoxic reagents in the lab, thereby making the method much greener and easier to handle. Mechanism studies confirmed for the first time that FeCl3 initially reacts with two equivalents of Hdipm to form [Fe(dipm)3] in the presence of a base in acetonitrile, followed by the formation of a five or six-membered ring intermediate between [Fe(dipm)3] and two hydroxyl groups of the substrate. A subsequent reaction between the cyclic intermediate and the alkylating agent results in selective alkylation of the substrate.
- Lv, Jian,Liu, Yu,Zhu, Jia-Jia,Zou, Dapeng,Dong, Hai
-
supporting information
p. 1139 - 1144
(2020/03/11)
-
- Both d - And l -Glucose Polyphosphates Mimic d - myo-Inositol 1,4,5-Trisphosphate: New Synthetic Agonists and Partial Agonists at the Ins(1,4,5)P3Receptor
-
Chiral sugar derivatives are potential cyclitol surrogates of the Ca2+-mobilizing intracellular messenger d-myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3]. Six novel polyphosphorylated analogues derived from both d- and l-glucose were synthesized. Binding to Ins(1,4,5)P3 receptors [Ins(1,4,5)P3R] and the ability to release Ca2+ from intracellular stores via type 1 Ins(1,4,5)P3Rs were investigated. β-d-Glucopyranosyl 1,3,4-tris-phosphate, with similar phosphate regiochemistry and stereochemistry to Ins(1,4,5)P3, and α-d-glucopyranosyl 1,3,4-tris-phosphate are full agonists, being equipotent and 23-fold less potent than Ins(1,4,5)P3, respectively, in Ca2+-release assays and similar to Ins(1,4,5)P3 and 15-fold weaker in binding assays. They can be viewed as truncated analogues of adenophostin A and refine understanding of structure-activity relationships for this Ins(1,4,5)P3R agonist. l-Glucose-derived ligands, methyl α-l-glucopyranoside 2,3,6-trisphosphate and methyl α-l-glucopyranoside 2,4,6-trisphosphate, are also active, while their corresponding d-enantiomers, methyl α-d-glucopyranoside 2,3,6-trisphosphate and methyl α-d-glucopyranoside 2,4,6-trisphosphate, are inactive. Interestingly, both l-glucose-derived ligands are partial agonists: they are among the least efficacious agonists of Ins(1,4,5)P3R yet identified, providing new leads for antagonist development.
- Shipton, Megan L.,Riley, Andrew M.,Rossi, Ana M.,Brearley, Charles A.,Taylor, Colin W.,Potter, Barry V. L.
-
p. 5442 - 5457
(2020/07/21)
-
- Highly Efficient Selective Benzylation of Carbohydrates Catalyzed by Iron(III) with Silver Oxide and Bromide Anion as Co-catalysts
-
A highly efficient, green, and regioselective method for the benzylation of diols and polyols was developed. With the use of Ag2O (0.6 equiv.) and tetrabutylammonium bromide (0.1 equiv.) as co-catalysts, the iron(III)-catalyzed benzylation reaction proceeded to completion at 40 °C within 2–3 h and gave the products in high yields with high regioselectivities. A mechanism involving the principle of enhanced basicity of Ag2O by soft anions was proposed.
- Ren, Bo,Lv, Jian,Zhang, Yu,Tian, Jun,Dong, Hai
-
p. 950 - 953
(2017/03/27)
-
- Regioselective alkylation of carbohydrates and diols: A cheaper iron catalyst, new applications and mechanism
-
As an extension of our previous research on the regioselective protection of carbohydrates and diols, we developed an iron catalyst, Fe(dibm)3 (dibm = diisobutyrylmethane), which has an unusually broad catalytic scope in the selective monoalkyl
- Ren, Bo,Yan, Ningning,Gan, Lu
-
p. 46257 - 46262
(2017/10/11)
-
- An Iron(III) Catalyst with Unusually Broad Substrate Scope in Regioselective Alkylation of Diols and Polyols
-
In this study, [Fe(dibm)3] (dibm=diisobutyrylmethane) is shown to have unusually broad scope as a catalyst for the selective monoalkylation of a diverse set of 1,2- and 1,3-diol-containing structures. The mechanism is proposed to proceed via a cyclic dioxolane-type intermediate, formed between the iron(III) species and two adjacent hydroxyl groups. This approach represents the first transition-metal catalysts that are able to replace stoichiometric amounts of organotin reagents in regioselective alkylation. The reactions generally lead to very high regioselectivities and high yields, on par with, or better than, previous methods used for regioselective alkylation.
- Ren, Bo,Ramstr?m, Olof,Zhang, Qiang,Ge, Jiantao,Dong, Hai
-
p. 2481 - 2486
(2016/02/12)
-
- Regioselective mono and multiple alkylation of diols and polyols catalyzed by organotin and its applications on the synthesis of value-added carbohydrate intermediates
-
A catalytic amount of dibutyltin dichloride was used to develop regioselective alkylation of diols and multiple alkylation of polyols. Alkyl groups, including allyl, alkynyl and long-chain alkyl groups, were successfully introduced to one or two hydroxyl
- Xu, Hengfu,Ren, Bo,Zhao, Wei,Xin, Xiaoting,Lu, Yuchao,Pei, Yuxin,Dong, Hai,Pei, Zhichao
-
p. 3490 - 3499
(2016/06/06)
-
- A green and convenient method for regioselective mono and multiple benzoylation of diols and polyols
-
An efficient method for regioselective benzoylation of diols and polyols was developed. The benzoylation is catalyzed by only 0.2 equiv of benzoate anion in acetonitrile with the addition of a stoichiometric amount of benzoic anhydride under very mild condition, leading to high yields. Compared with all other methods, this method shows particular advantage in regioselective multiple benzoylation of polyols, and in avoiding the use of any metal-based catalysts and any amine bases, which is more environment-friendly.
- Zhang, Xiaoling,Ren, Bo,Ge, Jiantao,Pei, Zhichao,Dong, Hai
-
supporting information
p. 1005 - 1010
(2016/02/03)
-
- Regioselective benzylation of diols and polyols by catalytic amounts of an organotin reagent
-
An efficient one-pot method for the selective benzylation of diols and polyols using 0.1 equiv. of organotin reagents and tetrabutylammonium bromide as catalyst has been developed. The diols and polyols containing a cis-vicinal diol were regioselectively
- Xu, Hengfu,Lu, Yuchao,Zhou, Yixuan,Ren, Bo,Pei, Yuxin,Dong, Hai,Pei, Zhichao
-
p. 1735 - 1740
(2014/06/09)
-
- Tin-mediated regioselective benzylation and allylation of polyols: Applicability of a catalytic approach under solvent-free conditions
-
The first catalytic version of the stannylene-mediated benzylation and allylation of polyols is reported. The methodology is based on a simple solvent-free protocol that significantly advances, in terms of both experimental ease and synthetic scope, the a
- Giordano, Maddalena,Iadonisi, Alfonso
-
p. 213 - 222
(2014/01/17)
-
- Halide promoted organotin-mediated carbohydrate benzylation: Mechanism and application
-
In the present study, the mechanistic origin of the promoted organotin-mediated carbohydrate benzylation by halides was explored by the comparison of the activation ability of halides on benzylation of methyl β-d-galactoside. It was demonstrated that the
- Zhou, Yixuan,Li, Jinyang,Zhan, Yingjie,Pei, Zhichao,Dong, Hai
-
supporting information
p. 2693 - 2700
(2013/03/28)
-
- Regioselectivity of tin-mediated benzylation of glycoside
-
Regioselectivity of methyl α-D-glucopyranoside benzylation using dibutyltin dimethoxide (DBDM) as stannylating agent was probed, general factors affecting regioselectivity have been examined. The results show the O-2 position of glucoside has advantage of
- Lou, Xin
-
p. 2281 - 2283
(2013/05/08)
-
- Acceptor-influenced and donor-tuned base-promoted glycosylation
-
Base-promoted glycosylation is a recently established stereoselective and regioselective approach for the assembly of di- and oligosaccharides by using partially protected acceptors and glycosyl halide donors. Initial studies were performed on partially methylated acceptor and donor moieties as a model system in order to analyze the key principles of oxyanion reactivities. In this work, extended studies on base-promoted glycosylation are presented by using benzyl protective groups in view of preparative applications. Emphases are placed on the influence of the acceptor anomeric configuration and donor reactivities.
- Boettcher, Stephan,Matwiejuk, Martin,Thiem, Joachim
-
body text
p. 413 - 420
(2012/05/05)
-
- Hydroxy group acidities of partially protected glycopyranosides
-
A comprehensive acidity study of carbohydrate hydroxy groups has been carried out. Relative acidities (Ke) were determined spectrophotometrically for partially methylated methyl α-D- glycopyranosides. Apparently, the acidity is strongly affected by intramolecular hydrogen bonding as well as stereochemistry and solvation. By comparison with pKe and pKa values of aliphatic alcohols and polyols the first estimation of the pKa values for partially protected glycopyranosides was obtained. These findings contribute to the understanding of the relative reactivities of carbohydrate hydroxy groups.
- Matwiejuk, Martin,Thiem, Joachim
-
scheme or table
p. 2180 - 2187
(2012/06/30)
-
- Azetidine iminosugars from the cyclization of 3,5-Di- O -triflates of α-furanosides and of 2,4-Di- O -triflates of β-pyranosides derived from glucose
-
Primary amines with either 3,5-di-O-ditriflates of α-furanosides or 2,4-di-O-triflates of β-pyranosides form bicyclic azetidines in high yield.
- Lenagh-Snow, Gabriel M. J.,Araujo, Noelia,Jenkinson, Sarah F.,Martinez, R. Fernando,Shimada, Yousuke,Yu, Chu-Yi,Kato, Atsushi,Fleet, George W.J.
-
p. 2142 - 2145
(2012/07/13)
-
- Total syntheses of HMP-Y1, hibarimicinone, and HMP-P1
-
Total syntheses of HMP-Y1, atrop-HMP-Y1, hibarimicinone, atrop-hibarimicinone, and HMP-P1 are described using a two-directional synthesis strategy. A novel benzyl fluoride Michael-Claisen reaction sequence was developed to construct the complete carbon sk
- Liau, Brian B.,Milgram, Benjamin C.,Shair, Matthew D.
-
supporting information
p. 16765 - 16772
(2013/01/15)
-
- Defining oxyanion reactivities in base-promoted glycosylations
-
Saccharide oxyanions obtained by base treatment could be employed in glycosylation to give oligosaccharides with high stereo- and regioselectivities.
- Matwiejuk, Martin,Thiem, Joachim
-
p. 8379 - 8381
(2011/09/14)
-
- A new cateh-and-release purification method using a levulinyl group as a tag and its application to oligosaccharide synthesis
-
Products possessing a levulinyl group were selectively isolated from reaction mixtures using a new resin-capture method and a polymer-supported aminooxy group. Successive treatment with NaOH in MeOH readily liberated purified products from the resins. Applications of this method to oligosaccharide syntheses are described. Copyright
- Izumi, Minoru,Okamoto, Ritsu,Sato, Mizuho,Nakajima, Shuhei,Baba, Naomichi,Fukase, Koichi
-
scheme or table
p. 1030 - 1031
(2009/12/02)
-
- Synthesis of positional thiol analogs of β-D-galactopyranose
-
Approaches toward the synthesis of thio-β-D-galactose derivatives are described. These compounds were prepared from the parent carbohydrates: D-galactose, methyl β-D-galactoside and methyl β-D-glucoside, respectively. It was found that not only the strategies of protecting group introduction and selective deprotection, but also the choices of solvent and nucleophilic reagent concentration were crucial to allow the efficient introduction of sulfur at different positions of the galactose ring. The effects from the solvent, the nucleophilic reagent concentration, and the protecting group patterns have been investigated. The results clearly show that ester protecting groups play highly important roles for the synthesis of thio-containing carbohydrates, requiring nonpolar solvents to suppress the neighboring group participation. For the Lattrell-Dax (nitrite-mediated) inversion reaction, employed in the synthetic route to the 2-thio-β-D- galactoside, intramolecular nucleophilic attack, as well as stronger stereospecific ester activation, are necessary to overcome hindrance from 4,6-O-benzylidene protection. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Pei, Zhichao,Dong, Hai,Caraballo, Remi,Ramstroem, Olof
-
p. 4927 - 4934
(2008/03/14)
-
- Galactose-phosphonates as mimetics of the sialyltransfer by trypanosomal sialidases
-
In an attempt to find competitive inhibitors of the trans-sialidase of the pathogen Trypanosoma cruzi, we have synthesized conjugates of carbocyclic sialylmimetics (e.g., cyclohexenephosphonates) and galactose derivatives. A trans-sialidase inhibition ass
- Busse, Heike,Hakoda, Mitsuru,Stanley, Matthew,Streicher, Hansjoerg
-
p. 159 - 194
(2008/02/11)
-
- Substituent effects on the SmI2/Pd(0)-promoted carbohydrate ring-contraction of 5-alkynylpyranosides
-
The effect of substituents on the reactivity and stereoselectivity of the SmI2/Pd(0)-promoted ring-contraction of 5-alkynylpyranosides has been examined using substrates substituted only at selected positions. While formation of 2-ethynylcyclopentanols takes place efficiently, an internal alkyne did not afford the expected product. The presence of peripheral alkoxy substituents leads to variable stereoselectivities that depend on the number and orientation of such groups. Thus, an isolated OBn substituent at C(3) (carbohydrate numbering) exerts a significant stereochemical control while additional substitution with the same group at C(4) either enhances or drastically reduces stereoselectivity depending on its orientation (α or β, respectively).
- Aurrecoechea, José M.,Gil, Jesús H.,López, Beatriz
-
p. 7111 - 7121
(2007/10/03)
-
- Synthesis of novel HIV-1 protease inhibitors based on carbohydrate scaffolds
-
The synthesis of peptidomimetic inhibitors of HIV-1 protease based on 6-deoxy-6-amino-β-D-glucopyranoside and 6-deoxy-6-amino-β-D-mannopyranoside scaffolds has been achieved. The inhibitors had IC50 values in the micromolar range. The results provide a platform for the development of more potent carbohydrate based inhibitors of HIV-1 and other aspartic proteases.
- Murphy, Paul V.,O'Brien, Julie L.,Gorey-Feret, Lorraine J.,Smith III, Amos B.
-
p. 2259 - 2271
(2007/10/03)
-
- Novel features of acceptor recognition by β-(1 ← 4)- galactosyltransferase
-
In order to understand how β-(1→4)-galactosyltransferase recognizes its glycosyl acceptor, substrate specificities were investigated using synthetic 2-acetamido-2-deoxy-D-glucopyranose (N-acetylglucosamine) derivatives in which the 1-, 2-, 3-, 4-, and 6-p
- Kajihara, Yasuhiro,Kodama, Hisashi,Endo, Tsuyoshi,Hashimoto, Hironobu
-
p. 361 - 378
(2007/10/03)
-
- Diastereoselective hydroboration of substituted exo-glucals revisited. A convenient route for the preparation of L-iduronic acid derivatives
-
Suitably protected derivatives of methyl 3-O-benzyl-6-deoxy-α-D-xylo- hex-5-enopyranoside, readily prepared from 3-O-benzyl-D-glucopyranose, were reacted with various boranes to prepare the corresponding L-idose components. Reaction of methyl 2-O-benzoyl-3-O-benzyl-6-deoxy-4-O-tert- butyldimethylsilyl-α-D-xylo-hex-5-enopyranoside with 9- borabicyclo[3.3.1]nonane (9-BBN) afforded an easily separable 9:1 L-ido:D- gluco mixture. The L-ido isomer was then transformed in a straightforward manner into suitably protected L-iduronic acid glycosyl donors (chloride, bromide, trichloroacetimidate) which could serve as highly elaborated building blocks in syntheses of L-iduronic acid containing glycosaminoglycan fragments. An unexpected side-reaction occurring in the preparation of 1-O- trichloroacetimidoyl derivatives is also reported.
- Rochepeau-Jobron, Laurence,Jacquinet, Jean-Claude
-
p. 395 - 406
(2007/10/03)
-
- REGIOSELECTIVE FORMATION OF DI-O-BENZYL-SUBSTITUTED HEXOPYRANOSIDES VIA STANNYLENE ACETAL INTERMEDIATES
-
The reactions of dibutylstannylene acetals derived from several methyl hexopyranosides with benzyl bromide have been investigated.These reactions occur readily in benzyl bromide at 85 deg C.At reaction times of one to two days, the major products are di-O-benzyl derivatives.In several cases, single di-O-benzyl derivatives are the predominant products: methyl α-D-glucopyranoside and methyl β-D-galactopyranoside gave the 2,6- and 3,6-di-O-benzyl ethers in 82 and 70percent yields, respectively.The species present in these reactions and the reaction pathway are discussed.
- Qin, Huiping,Grindley, T. Bruce
-
p. 475 - 490
(2007/10/02)
-
- Diastereoselective [2,3] Wittig rearrangement of carbohydrate-derived tertiary allylic ethers. 1. Synthesis of the C11-C18 subunit of herbimycin a fromD-glucose
-
Reductive fragmentation of the D-glucose derived iodopyranose 7 and diastereoselective [2,3] Wittig rearrangement of the resulting tertiary allylic ether affords trisubstituted olefin 19, comprising the C11-C18 segment of the benzoqu
- Eshelman, Jill E.,Epps, Janet L.,Kallmerten, James
-
p. 749 - 752
(2007/10/02)
-
- Synthesis of di- and tri-saccharides related to the polysaccharide from Streptococcus pneumoniae type 23 and a study of their inhibition in the precipitin reaction.
-
Syntheses of methyl 2-O-beta-L-rhamnopyranosyl-beta-D-galactopyranoside (9), methyl 2-O-alpha-L-rhamnopyranosyl-beta-D-galactopyranoside (13), and methyl 4-O-beta-D-glucopyranosyl-2-O-alpha-L-rhamnopyranosyl-beta-D- galactopyranoside (16) in good yields a
- Ray,Maddali,Roy,Roy
-
-
- Regioselective Monoalkylation of Non-protected Glycopyranosides by the Dibutyltin Oxide Method
-
Regioselective monoalkylation of some pento- and hexopyranosides (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) was examined by using the dibutyltin oxide method without protecting the hydroxyl groups.By this method, alkylation proceeds more or less in the same fashion as reported for acylation (through the formation of cyclic tin intermediates) and selectively activates an equatorial hydroxyl group which has an oxygenated function (OH or OMe) in a cis relationship at an adjacent position, even in the presence of a more reactive primary hydroxyl group.However, in some instances the position of activation is different.Various monoalkyl ethers thus prepared were identified by analyses of their carbon-13 nuclear magnetic resonance spectra.Keywords-regioselective monoalkylation; glycopyranoside; dibutyltin oxide; cis-vicinal glycol; benzylation; allylation; methoxymethylation; methylation;13C-NMR
- Haque, Mohammed Ekramul,Kikuchi, Tohru,Yoshimoto, Kimihiro,Tsuda, Yoshisuke
-
p. 2243 - 2255
(2007/10/02)
-
- 2-Substituted methyl alpha-D-galactopyranosides: synthesis and binding affinity for the A and B subunits of the Griffonia simplicifolia I isolectins.
-
The binding affinities of the N-acetyl, N-trifluoroacetyl, N-propionyl, N-formyl, N-benzoyl, N-p-nitrobenzoyl, N-p-aminobenzoyl, and N-methyl derivatives of methyl 2-amino-2-deoxy-alpha-D-galactopyranoside and the 2-O-acetyl, -benzoyl, -benzyl, and -methyl derivatives of methyl alpha-D-galactopyranoside for the A and B subunits of the Griffonia simplicifolia I isolectins have been determined by hapten inhibition analysis of a galactomannan-isolectin precipitation system. Models for these carbohydrate-protein interactions are presented together with an interpretation of the results on the basis of electronic and steric effects.
- Kaifu,Plantefaber,Goldstein
-
-
- Catalytic transfer hydrogenation of benzylic and styryl compounds with palladium/carbon and 2-propanol. Selective removal of O-benzyl groups from carbohydrate derivatives
-
2-Propanol is shown to be an effective hydrogen donor, in the presence of palladium/carbon, for catalytic transfer hydrogenation reactions of benzylic and styryl compounds, e.g., for the quantitative conversion of cinnamyl alcohol into 3-phenylpropanol.In the reduction of derivatives of cinnamic acid, decarboxylation also occurs.During the latter reaction, the phenyl group appears to function as an anchoring group for the palladium atom, because derivatives of phenylpropanoic acid are decarboxylated more readily than are those of phenylacetic acid.In hydrogenolysis reactions, aryl alcohols undergo disproportionation whereas benzyl ethers, represented by O-benzyl and related derivatives of carbohydrates, are smoothly cleaved.Although 2-propanol is less reactive as a hydrogen donor than formic acid, it exhibits greater selectivity, as illustrated by relative rates of hydrogenolysis of O-benzyl and O-benzylidene substituents.The use of alumina-supported palladium is more effective than palladium/carbon for promoting stepwise removal of O-benzyl substituents, as shown by the preparation of methyl 2-O-benzyl- and -3-O-benzyl-α-D-glucopyranoside from the 2,3-di-O-benzyl derivative.A possible relationship between the orientation of O-benzyl groups and the chemical shift differences between the diastereotopic benzylic protons is decribed.
- Rao, Vanga S.,Perlin, Arthur S.
-
p. 652 - 657
(2007/10/02)
-