The anomeric specificity of D-glucose metabolism in erythrocytes has been since 1985 the matter of extensive investigations reported in about ten publications. The present report aims at providing an integrated review...The anomeric specificity of D-glucose metabolism in erythrocytes has been since 1985 the matter of extensive investigations reported in about ten publications. The present report aims at providing an integrated review of the major findings on this issue.展开更多
Lactose powder consisting of α-D-lactose monohydrate and anhydrous β-D-lactose was nondestructively and quantitatively evaluated by transmission-type Terahertz time-domain spectroscopy (THz-TDS). An absorption with ...Lactose powder consisting of α-D-lactose monohydrate and anhydrous β-D-lactose was nondestructively and quantitatively evaluated by transmission-type Terahertz time-domain spectroscopy (THz-TDS). An absorption with peak at 39.7 cm-1 (1.19 THz) was assigned to be derived from anhydrous β-D-lactose, in addition to the absorptions due to α-D-lactose monohydrate with peak at 17.1 cm-1 (0.53 THz) and 45.6 cm-1 (1.37 THz). After deconvolution of the spectra using Lorentzian, integrated intensities of the absorptions with peak at 39.7 cm-1 and 45.6 cm-1 were uniquely dependent on the weight composition ratio of the α-and β-lactose powder. As a result, the net molar-ratio of the α-and β-lactose in lactose powder could be precisely evaluated by the integrated intensity ratio. Further, anomer content in lactose powder extracted from lactose solution was evaluated and the refined and unrefined features were shown by the evaluation method.展开更多
On two dimensional maps of <sup>1</sup>H-<sup>13</sup>C correlation spectroscopy (H-C COSY) analysis for the mannan of <i>Candida tropicalis</i>, nine cross peaks of anomeric proton...On two dimensional maps of <sup>1</sup>H-<sup>13</sup>C correlation spectroscopy (H-C COSY) analysis for the mannan of <i>Candida tropicalis</i>, nine cross peaks of anomeric proton and carbon were useful for the purpose of obtaining information on the chemical structure of this molecule. Namely, the mannans was comb-like structure constructed with the linear <i>α</i>-1,6-linked polymannnosyl backbone and several oligomannnosyl side chains composed of <i>α</i>-1,2-, <i>α</i>-1,3-, and <i>β</i>-1,2-linkages. Therefore, in the structural investigation of comb-like mannan, two-dimensional H-C COSY analysis is as useful as two-dimensional nuclear Hartmann-Hahn (HOHAHA) analysis.展开更多
Given the extreme complexity and diversity of carbohydrates,efficient approaches to the homogeneous oligosaccharide remain limited.Chemical synthesis represents one of the most reliable methods to access homogeneous s...Given the extreme complexity and diversity of carbohydrates,efficient approaches to the homogeneous oligosaccharide remain limited.Chemical synthesis represents one of the most reliable methods to access homogeneous samples,which mainly relies on the key glycosylation reaction.Consistent with enormous efforts to develop leaving groups for establishing robust glycosylation protocols,we herein disclose a structurally novel leaving group of 8-phenylethynyl-1-naphthoate that is able to enable efficient glycosylation reactions under the extremely mild condition of gold(I)-catalysis.Notably,the anomeric naphthoate possesses the unprecedent character of base-stability in sharp contrast to the conventional ester groups at anomeric position of carbohydrates,which endows high compatibility with a variety of chemical transformations.Furthermore,the present glycosylation protocol with 8-phenylethynyl-1-naphthoate as leaving group is able to realize minimally protected glycosylation processes.Mechanistic studies reveal a unique structure of 8-phenylethynyl-1-naphthoate that accounts for the reason for these characteristics.展开更多
D-Allose and its derivatives play important roles in the field of health care and food nutrition. Pure and well-defined Dallose derivatives can facilitate the elucidation of their structure-activity relationship as an...D-Allose and its derivatives play important roles in the field of health care and food nutrition. Pure and well-defined Dallose derivatives can facilitate the elucidation of their structure-activity relationship as an essential step for drug design. The LattrellDax epimerization, refers to the triflate inversion using nitrite reagent, is known as valuable method for the synthesis of rare D-allose derivatives. Here, the influence of protecting group patterns on the transformation efficiency of D-glucose derivatives into synthetically useful D-alloses and D-allosamines via the Lattrell-Dax epimerization was studied. For C3 epimerization of D-glucose derivatives bearing O2-acyl group, an anomeric configuration-dependent acyl migration from O2 to O3 was found. In addition, a neighbouring group participation effect-mediated SN1 nucleophilic substitution of the D-glucosamine bearing C2 trichloroacetamido(TCA) group in the Lattrell-Dax epimerization was dependent upon anomeric configuration. Thus, the effect of anomeric configuration on the LattrellDax epimerization of D-glucose suggests that β-D-glucosides with low steric hindrance at C2 should be better substrates for the synthesis of D-allose derivatives. Significantly, the efficient synthesis of the orthogonally protected D-allose 13 and D-allosamine 18 will serve well for further assembly of complex glycans.展开更多
The highly stereoselective synthesis of diverse medicinally valuable alkynyl C-glycosides under mild and green reaction conditions remains a great challenge.Herein,we wish to report a visible-light induced photocataly...The highly stereoselective synthesis of diverse medicinally valuable alkynyl C-glycosides under mild and green reaction conditions remains a great challenge.Herein,we wish to report a visible-light induced photocatalytic decarboxylative alkynylation approach.By utilizing an iridium photocatalyst in the presence of visible light,glycosyl radicals are in-situ generated via the decarboxylation of anomeric acids and efficiently coupled with a variety of ethynylbenziodoxolones(EBXs),which allows the facile synthesis of a variety of alkynyl C-glycosides in moderate to high yields and with excellent diastereoselectivity.展开更多
l-α-biaomo-2,3,4,6-tetra-O-acetyl-D-giucopyranose reacts with Grignard eagents prepared frorn the acnvated magnesium under very mild condition to ellord C- glucosides in a very high yield compared with Grignard Reage...l-α-biaomo-2,3,4,6-tetra-O-acetyl-D-giucopyranose reacts with Grignard eagents prepared frorn the acnvated magnesium under very mild condition to ellord C- glucosides in a very high yield compared with Grignard Reagent prepared from usual method.β-anomer predominates in the reaction, mixture The configuration of anomers was assigned by 13C NMR spectra.展开更多
文摘The anomeric specificity of D-glucose metabolism in erythrocytes has been since 1985 the matter of extensive investigations reported in about ten publications. The present report aims at providing an integrated review of the major findings on this issue.
文摘Lactose powder consisting of α-D-lactose monohydrate and anhydrous β-D-lactose was nondestructively and quantitatively evaluated by transmission-type Terahertz time-domain spectroscopy (THz-TDS). An absorption with peak at 39.7 cm-1 (1.19 THz) was assigned to be derived from anhydrous β-D-lactose, in addition to the absorptions due to α-D-lactose monohydrate with peak at 17.1 cm-1 (0.53 THz) and 45.6 cm-1 (1.37 THz). After deconvolution of the spectra using Lorentzian, integrated intensities of the absorptions with peak at 39.7 cm-1 and 45.6 cm-1 were uniquely dependent on the weight composition ratio of the α-and β-lactose powder. As a result, the net molar-ratio of the α-and β-lactose in lactose powder could be precisely evaluated by the integrated intensity ratio. Further, anomer content in lactose powder extracted from lactose solution was evaluated and the refined and unrefined features were shown by the evaluation method.
文摘On two dimensional maps of <sup>1</sup>H-<sup>13</sup>C correlation spectroscopy (H-C COSY) analysis for the mannan of <i>Candida tropicalis</i>, nine cross peaks of anomeric proton and carbon were useful for the purpose of obtaining information on the chemical structure of this molecule. Namely, the mannans was comb-like structure constructed with the linear <i>α</i>-1,6-linked polymannnosyl backbone and several oligomannnosyl side chains composed of <i>α</i>-1,2-, <i>α</i>-1,3-, and <i>β</i>-1,2-linkages. Therefore, in the structural investigation of comb-like mannan, two-dimensional H-C COSY analysis is as useful as two-dimensional nuclear Hartmann-Hahn (HOHAHA) analysis.
基金the financial support from the National Natural Science Foundation of China(22007080)Zhongshan Science and Technology Bureau(CXTD2022012)+3 种基金Youth Innovation Promotion Association of CAS(2020258)grateful to Hi-Level New R&D Institute(2019B090904008)High-Level Innovative Research Institute(2021B0909050003)from Department of ScienceTechnology of Guangdong Province.Prof.Hongbin Zhang(Yunnan University)is appreciated for the assistance on this project.
文摘Given the extreme complexity and diversity of carbohydrates,efficient approaches to the homogeneous oligosaccharide remain limited.Chemical synthesis represents one of the most reliable methods to access homogeneous samples,which mainly relies on the key glycosylation reaction.Consistent with enormous efforts to develop leaving groups for establishing robust glycosylation protocols,we herein disclose a structurally novel leaving group of 8-phenylethynyl-1-naphthoate that is able to enable efficient glycosylation reactions under the extremely mild condition of gold(I)-catalysis.Notably,the anomeric naphthoate possesses the unprecedent character of base-stability in sharp contrast to the conventional ester groups at anomeric position of carbohydrates,which endows high compatibility with a variety of chemical transformations.Furthermore,the present glycosylation protocol with 8-phenylethynyl-1-naphthoate as leaving group is able to realize minimally protected glycosylation processes.Mechanistic studies reveal a unique structure of 8-phenylethynyl-1-naphthoate that accounts for the reason for these characteristics.
基金the National Natural Science Foundation of China(Nos.21877052 and 21907039)the Natural Science Foundation of Jiangsu Province(Nos.BK20180030and BK20190575)+1 种基金the National First-class Discipline Program of Light Industry Technology and Engineering(No.LITE2018-14)the 111 Project(No.111-2-06)。
文摘D-Allose and its derivatives play important roles in the field of health care and food nutrition. Pure and well-defined Dallose derivatives can facilitate the elucidation of their structure-activity relationship as an essential step for drug design. The LattrellDax epimerization, refers to the triflate inversion using nitrite reagent, is known as valuable method for the synthesis of rare D-allose derivatives. Here, the influence of protecting group patterns on the transformation efficiency of D-glucose derivatives into synthetically useful D-alloses and D-allosamines via the Lattrell-Dax epimerization was studied. For C3 epimerization of D-glucose derivatives bearing O2-acyl group, an anomeric configuration-dependent acyl migration from O2 to O3 was found. In addition, a neighbouring group participation effect-mediated SN1 nucleophilic substitution of the D-glucosamine bearing C2 trichloroacetamido(TCA) group in the Lattrell-Dax epimerization was dependent upon anomeric configuration. Thus, the effect of anomeric configuration on the LattrellDax epimerization of D-glucose suggests that β-D-glucosides with low steric hindrance at C2 should be better substrates for the synthesis of D-allose derivatives. Significantly, the efficient synthesis of the orthogonally protected D-allose 13 and D-allosamine 18 will serve well for further assembly of complex glycans.
基金Financial support from the program of the National Natural Science Foundation of China(No.21871086,Y.-Q.Z.)is gratefully acknowledged.
文摘The highly stereoselective synthesis of diverse medicinally valuable alkynyl C-glycosides under mild and green reaction conditions remains a great challenge.Herein,we wish to report a visible-light induced photocatalytic decarboxylative alkynylation approach.By utilizing an iridium photocatalyst in the presence of visible light,glycosyl radicals are in-situ generated via the decarboxylation of anomeric acids and efficiently coupled with a variety of ethynylbenziodoxolones(EBXs),which allows the facile synthesis of a variety of alkynyl C-glycosides in moderate to high yields and with excellent diastereoselectivity.
文摘l-α-biaomo-2,3,4,6-tetra-O-acetyl-D-giucopyranose reacts with Grignard eagents prepared frorn the acnvated magnesium under very mild condition to ellord C- glucosides in a very high yield compared with Grignard Reagent prepared from usual method.β-anomer predominates in the reaction, mixture The configuration of anomers was assigned by 13C NMR spectra.
