4132-26-7Relevant academic research and scientific papers
A Laser Flash Photolysis Derived Study of a Glycosylidene Carbene
Vasella, Andrea,Briner, Karin,Soundararajan, N.,Platz, Matthew S.
, p. 4741 - 4744 (1991)
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.
Glycosylidene Carbenes. Part 18. Insertion of Glycosylidene Carbenes into the Sn-H Bond of Tributyl and Triphenylstannane: A Synthesis of Stannoglycosides
Uhlmann, Peter,Nanz, Daniel,Bozo, Eva,Vasella, Andrea
, p. 1430 - 1440 (1994)
Insertion of the glycosylidene carbenes, derived from the gluco- and the manno-diazirines 1 and 2, into the Sn-H bond of R3SnH (R = Bu of Ph) leads to the fully substituted stannoglycosides 3-8 (53 - 77percent).The 1,2-cis-configurated products are formed
Straightforward synthesis of protected 2-hydroxyglycals by chlorination-dehydrochlorination of carbohydrate hemiacetals
Choutka, Jan,Kratochvíl, Michal,Parkan, Kamil,Pohl, Radek,Zyka, Jakub
, (2020/08/24)
A straightforward and scalable method for the synthesis of protected 2-hydroxyglycals is described. The approach is based on the chlorination of carbohydrate-derived hemiacetals, followed by an elimination reaction to establish the glycal moiety. 1,2-dehy
Polymethylhydrosiloxane (PMHS): A convenient option for synthetic applications of the iodine/silane combined reagent - Straightforward entries to 2-hydroxyglycals and useful building-blocks of glucuronic acid and glucosamine
Giordano, Maddalena,Iadonisi, Alfonso
, p. 125 - 131 (2013/02/25)
Polymethylhydrosiloxane (PMHS) proved to be a practically convenient alternative to triethylsilane in a large set of synthetic elaborations entailing the quick generation of glycosyl iodides with a iodine/silane combined reagent. In addition, the scope of this combined reagent was expanded to the especially fast generation of 2-acetoxyglycals, and the rapid synthesis of useful building-blocks of D-glucuronic acids and D-glucosamine. All the synthetic targets were obtained in especially short times either via one-pot procedures or through experimental sequences devoid of laborious chromatographical purifications of intermediates. Polymethylhydrosiloxane (PMHS) is a practically convenient alternative to triethylsilane in a large set of synthetic elaborations entailing the quick generation of glycosyl iodides with a iodine/silane combined reagent. Copyright
Glycosyl iodides are highly efficient donors under neutral conditions
Hadd, Michael J.,Gervay, Jacquelyn
, p. 61 - 69 (2007/10/03)
Glycosyl iodides have been prepared and subjected to glycosylation under neutral conditions. The reactions are highly efficient, giving α glycosides even with sterically demanding glycosyl acceptors. Glucosyl iodides react with allyl alcohol slowest and require refluxing conditions. Galactosyl iodides are intermediate in reactivity, providing the allyl glycoside in 3 h at room temperature, whereas glycosylation of fucosyl iodides occurs in less than 1 h under similar conditions. The scope and limitations of the reactions were demonstrated with a variety of acceptors, including an anomeric hydroxyl group, to give trehalose analogs. β-Selective glycosylation of glucosyl iodides, in the absence of C-2 participation, could be achieved by simply changing the solvent from benzene to acetonitrile. Copyright (C) 1999 Elsevier Science Ltd.
Anionic Additions to Glycosyl Iodides: Highly Stereoselective Syntheses of β C-, N-, and O-Glycosides
Gervay, Jacquelyn,Hadd, Michael J.
, p. 6961 - 6967 (2007/10/03)
Classically, glycosyl halides are activated as glycosyl donors by metal chelation under KoenigsKnorr or Helferich conditions. These reactions often proceed through oxonium formation, and the stereochemical outcome is dictated by the anorneric effect and/or the nature of the protecting group on the C2 hydroxyl. Alternatively, glycosyl halides may undergo direct displacement of the halide by an incoming nucleophile in an SN2 mechanism. The latter reaction is far less common, and before this study it was primarily performed with glycosyl bromides. Having recently shown that both α and βglycosyl iodides could be efficiently generated, we embarked upon an investigation of nucleophilic additions to glycosyl iodides. The studies reported herein show that additions of stabilized anions to α-glycosyl iodides proceed with inversion of stereochemistry to give β-glycosides, even in the absence of a C2 participatory group. Glucosyl, galactosyl, and mannosyl iodides were studied, and the combined results indicate that the reactivity of 2,3,4,6-tetra-O-benzyl-α-D-galactosyl iodide > 2,3,4,6-tetra-O-benzyl-α-D-glucosyl iodide > 2,3,4,6-tetra-O-benzyl-α-D-mannosyl iodide. Both the glucosy] and galactosyl iodides are susceptible to E-2 elimination when treated with highly basic anions. In contrast, the mannosyl iodide undergoes substitution to give the 1,2 cis configuration. The overall sequence involves reaction of an anorneric acetate with trimethylsilyl iodide with in vacua removal of the resulting trimethylsilyl acetate. The iodide is then treated with a nucleophile without further characterization. A variety of nucleophiles were stereoselectively added to the glycosyl halides providing β-, C-, N-, and O-glycosides.
Glycosylidene Carbenes Part 12, A New Synthesis and Some Reactions of Spirooxiranes
Vasella, Andrea,Dhar, Preeti,Witzig, Christian
, p. 1767 - 1778 (2007/10/02)
The diazirine 1, upon thermolysis or photolysis in either acetone or cyclohexanone, at different concentrations, yielded the spiro epoxides 2 and 3, and 4 and 5, respectively (Scheme 1).Yields of 2 and 3 depended both on the temperature and the concentrat
Glycosylidene Carbenes, Part 10. Regioselective Glycosidation of 4,6-O-Benzylidene-D-altropyranosides
Bozo, Eva,Vasella, Andrea
, p. 2613 - 2633 (2007/10/02)
Glycosidation by the diazirine 1, the trichloroacetimidate 4, and the bromide 5 of the altro-diol 2, possessing an intramolecular H-bond (HO-C(3) to O-C(1)) in solution, but not in the solid state, proceeds with high and complementary regioselectivity.From 2 and 1, one obtains mostly the 1,2-linked disaccharides 10 and 11 (β-D > α-D), together with the 1,3-linked isomers 12 and 13 (α-D > β-D; 1,2-/1,3-linked products ca.9:1), the demethylated 1,3-linked disaccharides 24-27, the trisaccharides 19-22, the lactone azines 23, and the hydroxyglucal 18, while 2 reacted with 4 or 5 to yield mostly the 1,3-linked disaccharides (1,2-/1,3-linked products ca. 1:9).The disaccharides were additionally characterized as acetates (-> 14-17, 28-31).Yields and stereoselectivity depended upon the donor, stoichiometry, solvent, temperature, and concentration.Glycosidation of the 1,3-linked disaccharides with 1 yielded the trisaccharides 19-22.Reaction of the β-D-altro-diol 3 with 1 gave the 1,2- and 1,3-linked disaccharides 32/33 and 34/35 in a 1:1 ratio, characterized as the acetates 36-39, while glycosidation with 5 according to Lemieux proceeded regioselectively (1,2-/1,3-linked products 91:9).The monotosylates 6 and 7 reacted with 1 to yield the anomeric pairs 40/41, and 42/43 of the tosylated disaccharides; the oxiranes 44 and 45 were not observed.
