847237-56-3Relevant academic research and scientific papers
Chiral recognition of amino-acid esters by a glucose-derived macrocyclic receptor
Dominique, Pit,Schnurr, Martin,Lewandowski, Bartosz
supporting information, p. 3476 - 3479 (2021/04/12)
We report a glucose-based crown ether capable of chiral recognition of a wide range of amino-acid methyl esters in aqueous environments. The enantioselectivities towards amino-acids with extended hydrophobic side chains displayed by the glucose-derived ma
The building blocks of cellulose: The intrinsic conformational structures of cellobiose, its epimer, lactose, and their singly hydrated complexes
Cocinero, Emilio J.,Gamblin, David P.,Davis, Benjamin G.,Simons, John P.
supporting information; experimental part, p. 11117 - 11123 (2009/12/03)
A combination of vibrational spectroscopy conducted under molecular beam conditions and quantum chemical calculation has established the intrinsic three-dimensional structures of the cellulose disaccharide and, focusing on the critical β1,4-linkage at the nonreducing end of the growing cellulose polymer, its C-4′ epimer. Left to their own devices they both adopt a cis (anti-φ/syn-ψ) glycosidic configuration, supported in the epimer by strong, cooperative inter-ring hydrogen bonding. In the cellulose disaccharide, however, where the OH-4′(Glc) group is equatorial, the cooperativity is reduced and the corresponding inter-ring hydrogen bonding is relatively weak. The cis conformational preference is still retained in their singly hydrated complexes. In the cellulose disaccharide insertion of the water molecule at the favored binding site between OH-4′ and the neighboring hydroxyl group OH-6′ promotes a structural reorganization to create a configuration that parallels that of its unhydrated epimer and greatly strengthens the inter-ring hydrogen bonding. In the C-4′ epimer, the axial orientation of OH-4′ blocks this binding site and the bound water molecule simply adds on at the end of the (OH-O)n chain, which has a negligible effect on the (already strong) inter-ring bonding. The implications of these results are discussed with respect to the structure and insolubility of native cellulose polymers.
The First Total Syntheses of Enantiomerically Pure Naturally Occuring Ellagitannins Gemin D and its Regioisomer Hippomanin A
Khanbabaee, Karamali,Loetzerich, Kerstin,Borges, Markus,Grosser, Mathias
, p. 159 - 166 (2007/10/03)
The total syntheses of naturally occuring ellagitannins gemin D (1) and its regioisomer hippomanin A (2) are reported. In addition, the phase-transfer catalyzed benzylation reaction of the 2,3-glucopyranoside diols 3-7 is described. Our studies have illustrated the influence of the structure of 2,3-glucopyranoside diols on the regioselectivity of the phase-transfer catalyzed benzylation at their free 2,3-OH groups. We could show, that both phase-transfer catalyzed benzylations of 2,3-glucopyranoside diols using tetrabutylammonium hydrogensulfate (Bu4NHSO4) or using tetrabutylammonium iodide (Bu4NI) disfavour the formation of the corresponding 3-O-monobenzylated products and preferentially give the 2-O-monobenzylated products. However, the ratio of the generated 2- versus 3-O-mono- and 2,3-dibenzylated products from these reactions also strongly depends upon the nature of the starting materials. The glucopyranosides 3 and 4 are the first examples, which allow the completely regioselective monobenzylation at the 2-OH positions by a phase-transfer catalyzed reaction.
