4132-29-0Relevant articles and documents
Glycosyl trichloroacetylcarbamate: A new glycosyl donor for O-glycosylation
Jayakanthan,Vankar, Yashwant D.
, p. 2688 - 2692 (2005)
Glycosyl trichloroacetylcarbamates, readily obtained by reacting 1-hydroxy sugars with trichloroacetylisocyanate, have been found as excellent glycosyl donors, and the corresponding O-glycosides are formed in good to excellent yields with a fairly good degree of selectivity.
Chemoselectivity in Self-Promoted Glycosylation: N- vs. O-Glycosylation
Pedersen, Christian Marcus,Pinna, Alessandro
, (2020)
Self-promoted glycosylation using trichloroacetimidates and sulfonamides have recently been developed. In this communication, we study the parameters controlling the chemoselectivity between a nucleophilic sulfonamide nitrogen and an alcohol, both contain
An Unexpected FeCl 3/C-Catalyzed β-Stereoselective Glycosylation in the Presence of the C(2)-Benzyl Group
Guo, Hong,Li, Juan,Si, Wenshuai,Tang, Jie,Tang, Tianjun,Wang, Zhongfu,Yang, Guofang,Zhang, Jianbo
, p. 2984 - 3000 (2019/07/22)
An efficient and completely β-stereoselective glycosylation that did not rely on neighboring group participation is described using 2-20 molpercent FeCl 3 /C as the catalyst and benzylated propargyl glycosides as the donors to reach yields up to 96percent under mild condition. With an octatomic-ring intermediate at the α-face of FeCl 3 /C with alkyne of propargyl glycosides, a panel of aglycones comprising aliphatic, alicyclic, unsaturated alcohols, halogenated alcohols, and phenols with different substitution were examined successfully for the exclusive β-stereoselective glycosylation reaction.
An Empirical Understanding of the Glycosylation Reaction
Chatterjee, Sourav,Moon, Sooyeon,Hentschel, Felix,Gilmore, Kerry,Seeberger, Peter H.
, p. 11942 - 11953 (2018/09/27)
Reliable glycosylation reactions that allow for the stereo- and regioselective installation of glycosidic linkages are paramount to the chemical synthesis of glycan chains. The stereoselectivity of glycosylations is exceedingly difficult to control due to the reaction's high degree of sensitivity and its shifting, simultaneous mechanistic pathways that are controlled by variables of unknown degree of influence, dominance, or interdependency. An automated platform was devised to quickly, reproducibly, and systematically screen glycosylations and thereby address this fundamental problem. Thirteen variables were investigated in as isolated a manner as possible, to identify and quantify inherent preferences of electrophilic glycosylating agents (glycosyl donors) and nucleophiles (glycosyl acceptors). Ways to enhance, suppress, or even override these preferences using judicious environmental conditions were discovered. Glycosylations involving two specific partners can be tuned to produce either 11:1 selectivity of one stereoisomer or 9:1 of the other by merely changing the reaction conditions.
Carbohydrates dithiocarbonic acid esters and their application in glycosylation reactions
Slusarczyk,Sieron,Szeja
, p. 49 - 54 (2007/10/03)
Allyl dithiocarbonic acid esters are used as efficient glycosyl donors in the presence of soft activators. Different glycosides are obtained in good yields, isomer α being the main product.
Investigations on leaving group based intra- versus intermolecular glycoside bond formation
Scheffler, G?tz,Behrendt, Michael E.,Schmidt, Richard R.
, p. 3527 - 3539 (2007/10/03)
Ligation of the glyscosyl donor to the glycossyl acceptor through th eleaving group was performed with the aim of enforcing glycoside bond formation by an intramolecular (1.x)-shift. To this end, systheses of alkoxypropenly (27a and b), and 7-alkoxy-4-oxaheptadienly thioglucopyranoside derivatives (35a, b and d) were carried out. Thier activation with thiophilic systems gave the expected glucopyranosides 5a, b and d in up to high chemical yields, yet modest anomeric control. Competition experiments showed that an intermolecular reaction course is favored in these reactions, although model considerations imply that convenient intramolecular (1,3)-, (1,4)- (1,5)-, and (1,9)-shifts, respectively, of the glycosyl donor to the acceptor are possible.
Leaving group based intramolecular glycoside bond formation
Behrendt, Michael E.,Schmidt, Richard R.
, p. 6733 - 6736 (2007/10/02)
Sterically crowded β-hydroxy-substituted glucosyl carboxylates 4α,β furnish with strong alkylating agents 5a-c in the presence of base diastereoselectively α- or β-glucosides 6a-c, respectively; in addition, β-lactone 7 is formed. The reaction is discusse
Glycosylidene Carbenes. Part 6. Synthesis of Alkyl and Fluoroalkyl Glycosides
Briner, Karin,Vasella, Andrea
, p. 621 - 637 (2007/10/02)
The synthesis of glycosides from the diazirine 1 and a range of alcohols under thermal and/or photolitic conditions are described.Yields and diastereoselectivities depend upon the pKHA values of the alcohols, the solvent, and the reaction temperature.The glycosidation of weakly acidic alcohols (MeOH, EtOH, i-PrOH, and t-BuOH, 1 equiv. each) in CH2Cl2 at room temperature leads to the glycosides 2-5 in yields between 60 and 34percent (Scheme I and Table 1) At -70 to -60 deg, yields are markedly higher.In CH2Cl2, diastereoselectivities are very low.In THF, at -70 to -60 deg, however, glycosidation of i-PrOH leads to α-D-/β-D-4 in a ratio of 8:92.More strongly acidic alcohols, such as CF3CH2OH, (CF3)2CHOH, and (CF3)2C(Me)OH, and the highly fluorinated long-chain alcohols CF3(CF2)5(CH2)2OH (11) and CHF2(CF2)9CH2OH (13) react (CH2Cl2, r.t.) in yields between 73 and 85percent and lead mainly to the β-D-glucosides β-D-6 to β-D-8, β-D-12, and β-D-14 (d.e. 14-68percent).Yields and diastereoselectivities are markedly improved, when toluene, dioxane, 1,2-dimethoxyethane, or THF are used, as examined for the glycosidation of (CF3)2C(Me)OH, yielding (1,2-dimethoxyethane, 25 deg) 80percent of α-D-/β-D-8 in a ratio of 2:98 (d.e. 96percent; Table 4).In EtCN, (CF3)2C(Me)OH yields up to 55percent of the imidate 10.Glycosidation of di-O-isopropylidene-glucose 15 leads to 16 (CH2Cl2, r.t; 65percent, α-D/β-D=33:67).That glycosidation occurs by initial protonation of the intermediate glycosylidene carbene is evidenced, for strongly acidic alcohols, by the formation of 10, derived from the attack of (CF3)2MeCO(1-) on an intermediate nitrilium ion (Scheme 4), and, for weakly acidic alcohols, by the formation of α-D-9 and β-D-9, derived by attack of i-PrO(1-) on intermediate tetrahydrofuranylium ions.A working hypothesis is presented (Scheme 3).The diastereoselectivities are rationalized on the basis of a protonation in the ? plane of the intermediate carbene, the stabilization of the thereby generated ion pair by interaction with the BnO-C(2) group, with the solvent, and/or with the alcohol, and the final nucleophilic attack by RO(1-) in the ? plane of the (solvated) oxonium ion.
A Laser Flash Photolysis Derived Study of a Glycosylidene Carbene
Vasella, Andrea,Briner, Karin,Soundararajan, N.,Platz, Matthew S.
, p. 4741 - 4744 (2007/10/02)
Laser flash photolysis of a glycosylidene-derived diazirine produces the corresponding carbene.The carbene can be intercepted with pyridine to form an ylide.The absolute rate constants for the reaction of the glycosylidene carbene with alcohols can be obtained by monitoring the absolute rate of formation of the pyridinium ylide.The kinetic data favors a mechanism involving a proton transfer from the alcohol to the carbene.
