5391-17-3Relevant academic research and scientific papers
Synthesis of alkyl α- and β-d-glucopyranoside-based chiral crown ethers and their application as enantioselective phase-transfer catalysts
Pálv?lgyi, ádám,Rapi, Zsolt,Ozohanics, Olivér,Tóth, Gábor,Keglevich, Gy?rgy,Bakó, Péter
, p. 1627 - 1645 (2017/11/16)
Chiral monoaza-15-crown-5-type lariat ethers annelated to alkyl 4,6-O-benzylidene-α- and β-d-glucopyranosides have been synthesized. These macrocycles generated significant asymmetric induction as phase-transfer catalysts in a few two-phase reactions. The catalytic effect of the lariat ethers with methoxy, ethoxy, and i-propoxy substituents on C-1 of the sugar unit in both α and β positions was compared. In liquid–liquid two-phase reactions, the nature and position of the substituents did not have much effect. The α-anomers were somewhat more efficient in terms of enantioselectivity than the β forms. In asymmetric Darzens condensations, in the epoxidation of trans-chalcone, in the Michael addition of β-nitrostyrene and diethyl acetamidomalonate, and in the reaction of 2-benzylidene-1,3-indandione with diethyl bromomalonate, maximum enantioselectivities of 73, 94, 78, and 72%, respectively, were obtained in presence of glucopyranoside-based lariat ethers as catalysts.
Selective C?O Bond Cleavage of Sugars with Hydrosilanes Catalyzed by Piers’ Borane Generated In Situ
Zhang, Jianbo,Park, Sehoon,Chang, Sukbok
supporting information, p. 13757 - 13761 (2017/10/09)
Described herein is the selective reduction of sugars with hydrosilanes catalyzed by using Piers’ borane [(C6F5)2BH] generated in situ. The hydrosilylative C?O bond cleavage of silyl-protected mono- and disaccharides in the presence of a (C6F5)2BH catalyst, generated in situ from (C6F5)2BOH, takes place with excellent chemo- and regioselectivities to provide a range of polyols. A study of the substituent effects of sugars on the catalytic activity and selectivity revealed that the steric environment around the anomeric carbon (C1) is crucial.
Metal-catalyzed stereoselective and protecting-group-free synthesis of 1,2-cis-glycosides using 4,6-dimethoxy-1,3,5-triazin-2-yl glycosides as glycosyl donors
Tanaka, Tomonari,Kikuta, Naoya,Kimura, Yoshiharu,Shoda, Shin-Ichiro
supporting information, p. 846 - 848 (2015/06/22)
4,6-Dimethoxy-1,3,5-triazin-2-yl glycosides, glycosyl donors prepared in one step from free saccharides without protection of the hydroxy groups, were stereoselectively and equivalently converted to the corresponding 1,2-cis-glycosides by using a catalytic amount of metal catalyst. This reaction was successfully applied not only to monosaccharides, but also to di- and oligosaccharides.
Solvent and α-secondary kinetic isotope effects on β-glucosidase
Xie, Miaomiao,Byers, Larry D.
, p. 1776 - 1781 (2015/03/30)
β-Glucosidase from sweet almond is a retaining, family 1, glycohydrolase. It is known that glycosylation of the enzyme by aryl glucosides occurs with little, if any, acid catalysis. For this reaction both the solvent and α-secondary kinetic isotope effects are 1.0. However, for the deglucosylation reaction (e.g., kcat for 2,4-dinitrophenyl-β-D-glucopyranoside) there is a small solvent deuterium isotope effect of 1.50 (± 0.06) and an α-secondary kinetic isotope effect of 1.12 (± 0.03). For aryl glucosides, kcat/KM is very sensitive to the pKa of the phenol leaving group [βlg - 1; Dale et al., Biochemistry 25 (1986) 2522-2529]. With alkyl glucosides the βlg is smaller (between - 0.2 and - 0.3) but still negative. This, coupled with the small solvent isotope effect on the pH-independent second-order rate constant for the glucosylation of the enzyme with 2,2,2-trifluoroethyl-β-glucoside [D2O(kcat/KM) = 1.23 (± 0.04)] suggests that there is more glycone-aglycone bond fission than aglycone oxygen protonation in the transition state for alkyl glycoside hydrolysis. The kinetics constants for the partitioning (between water and various alcohols) of the glucosyl-enzyme intermediate, coupled with the rate constants for the forward (hydrolysis) reaction provide an estimate of the stability of the glucosyl-enzyme intermediate. This is a relatively stable species with an energy about 2 to 4 kcal/mol higher than that of the ES complex. This article is part of a Special Issue entitled: Enzyme Transition States from Theory and Experiment.
Direct glycosylation of bioactive small molecules with glycosyl iodide and strained olefin as acid scavenger
Gu, Xiangying,Chen, Lin,Wang, Xin,Liu, Xiao,You, Qidong,Xi, Wenwei,Gao, Li,Chen, Guohua,Chen, Yue-Lei,Xiong, Bing,Shen, Jingkang
, p. 1100 - 1110 (2014/03/21)
A new strategy for diversity-oriented direct glycosylation of bioactive small molecules was developed. This reaction features (-)-β-pinene as acid scavenger and work with glycosyl iodides under mild conditions. With the aid of RP-HPLC and chiral SFC separation techniques, the new direct glycosylation proved effective at gram scale on bioactive small molecules including AZD6244, podophyllotoxin, paclitaxel, and docetaxel. Interesting glycoside derivatives were efficiently created with good yields and 1,2-cis selectivity.
Protection-free synthesis of alkyl glycosides under hydrogenolytic conditions
Ishihara, Masaki,Takagi, Yuka,Li, Gefei,Noguchi, Masato,Shoda, Shin-Ichiro
supporting information, p. 1235 - 1237 (2013/10/22)
A convenient protection-free synthetic route for the preparation of alkyl glycosides has been developed. The alcoholysis of one-step preparable glycosyl donors, 4,6-dibenzyloxy-1,3,5-triazin-2-yl (DBT) glycosides, under hydrogenolytic conditions gave the corresponding glycosides in good yields without the addition of any acid promoters. The method could be successfully applied to the glycosylation of an acidlabile oligosaccharide.
Isolation and characterization of a novel α-glucosidase with transglycosylation activity from Arthrobacter sp. DL001
Zhou, Kun,Luan, Hong-Wei,Hu, Ying,Ge, Guang-Bo,Liu, Xing-Bao,Ma, Xiao-Chi,Hou, Jie,Wang, Xiu-Li,Yang, Ling
experimental part, p. 48 - 57 (2012/09/07)
A strain of Arthrobacter sp. DL001 with high transglycosylation activity was successfully isolated from the Yellow Sea of China. To purify the extracellular enzyme responsible for transglycosylation, a four-step protocol was adopted and the enzyme with electrophoretical purity was obtained. The purified enzyme has a molecular mass of 210 kDa and displays a narrow hydrolysis specificity towards α-1,4-glucosidic bond. Its hydrolytic activity was identified as decreasing in the order of maltotriose > panose > maltose. Only 3.61% maltose activity occurs when p-nitrophenyl α-d-glycopyranoside serves as a substrate, suggesting that this enzyme belongs to the type II α-glucosidase. In addition, the enzyme was able to transfer glucosyl groups from the donors containing α-1,4-glucosidic bond specific to glucosides, xylosides and alkyl alcohols in α-1,4- or α-1,6-manners. A decreased order of activity was observed when maltose, maltotriose, panose, β-cyclodextrin and soluble starch served as glycosyl donors, respectively. When maltose was utilized as a donor and a series of p-nitrophenyl-glycosides as acceptors, the glucosidase was capable of transferring glucosyl groups to p-nitrophenyl-glucosides and p-nitrophenyl-xylosides in α-1,4- or α-1,6-manners. The yields of p-nitrophenyl-oligosaccharides could reach 42-60% in 2 h. When a series of alkyl alcohols were utilized as acceptors, the enzyme exhibited its transglycosylation activities not only to the primary alcohols but also to the secondary alcohols with carbon chain length 1-4. Therefore, all the results indicated that the purified α-glucosidase present a useful tool for the biosynthesis of oligosaccharides and alkyl glucosides.
Efficient glycosylation of unprotected sugars using sulfamic acid: A mild eco-friendly catalyst
Guchhait, Goutam,Misra, Anup Kumar
experimental part, p. 52 - 57 (2012/01/15)
Sulfamic acid, a mild and environmentally benign catalyst has been successfully used in the Fischer glycosylation of unprotected sugars for the preparation alkyl glycosides. A diverse range of aliphatic alcohols have been used to prepare a series of alkyl glycosides in good to excellent yield.
Citrusosides A-D and furanocoumarins with cholinesterase inhibitory activity from the fruit peels of citrus hystrix
Youkwan, Juthamanee,Sutthivaiyakit, Somyote,Sutthivaiyakit, Pakawadee
supporting information; scheme or table, p. 1879 - 1883 (2011/02/26)
Four new compounds, citrusosides A-D (1-4), and 15 known compounds were isolated from the hexanes and CH2Cl2 extracts of the peels of Citrus hystrix fruits. Compound 1 is a 1-O-isopropyl-6-O-β-d- glucopyranosyl ester of 5″,9″-dimethyl-2″,8″-decadienoic acid. Compounds 2-4 possess a 1-O-isopropyl-β-d-glucopyranosyl and a dihydroxyprenylfuranocoumarin moiety conjugated to the 3-hydroxy-3- methylglutaric acid as diesters. Several furanocoumarins were evaluated for their cholinesterase inhibitory activity. (R)-(+)-6′-Hydroxy-7′- methoxybergamottin, (R)-(+)-6′,7′-dihydroxybergamottin, and (+)-isoimparatorin showed IC50 values of 11.2 ± 0.1, 15.4 ± 0.3, and 23 ± 0.2 μM, respectively. Bioassay results indicated that the presence of a dioxygenated geranyl chain in the test compounds is crucial for the inhibitory activity.
Cyanogenic and non-cyanogenic glycosides from Manihot esculenta (euphorbiaceae)
Anam, Edet M.
experimental part, p. 423 - 429 (2009/12/24)
A novel cyanogenic glycoside, 2-((6-0-(β-D-apiofuranosyl)-β- D-glucopyranosyloxy)-2-methylbutanenitrile, I, three novel non- cyanogenic glycosides, (2S)-((6-0-(β-D-apiofuranosyI)-β-D-gluco- pyranosyloxy) butane, 2; 2-((6-0-(β-D-apiofuranosyl)-β-D-gluco- pyranosyloxy) propane, 3, ethyl p-D-glucopyranosidc, 4, two known cyanogenic glycosides, (R)-2-(β-D-Glucopyranosyloxy)-2- methyl butanenitrile (lotaustralin), 5, 2-(β-D-Glucopyranosyloxy)- 2-methylpropane nitrile (linamarin), 6 have been isolated from ethanolic extract of the fresh rootcortex of Manihot esculenta. Lotaustralin and linamarin and two flavonoid glycosides, kaempferol-3-O- rutinosidc, 7 and quercctin-3-O-rutinoside, 8 have been isolated from the methanol extract of the fresh leaves of the same plant.
