Capillary gas-chromatographic analysis of monosaccharides: Improvements and comparisons using trifluoroacetylation and trimethylsilylation of sugar O-benzyl- and O-methyl-oximes
作者:Mark A. Andrews
DOI:10.1016/0008-6215(89)85001-3
日期:1989.12
Two new procedures for the gas-chromatographicanalysis of monosaccharides are reported. One involves derivatization of the sugars by reaction with O-benzylhydroxylamine followed by trifluoroacetylation with N-methylbis(trifluoroacetamide) and chromatography on a DB-1701 capillary column. This technique probably provides the best resolution achieved to date of the C3-C6 aldoses, as well as of the corresponding
Development of a Karplus equation for 3JCOCH in ester-functionalized glucopyranoses and methylglucuronate.
作者:Sven Hackbusch、Amelia Watson、Andreas H. Franz
DOI:10.24820/ark.5550190.p010.113
日期:——
Empirical Karplusequations are very useful in the conformational analysis of flexible molecules, especially with regards to carbohydrates. The C(sp2)OCH dihedral angle of ester-functionalized carbohydrates, however, is not well described by widely used Karplusequations for COCH dihedral angles, because they are based on C(sp3)OCH data. Herein, we propose a three parameter Karplusequation of the form
TMSOTf-Catalyzed Silylation: Streamlined Regioselective One-Pot Protection and Acetylation of Carbohydrates
作者:A. Abragam Joseph、Ved Prakash Verma、Xin-Yi Liu、Chia-Hui Wu、Vijay M. Dhurandhare、Cheng-Chung Wang
DOI:10.1002/ejoc.201101267
日期:2012.2
A highly efficient TMSOTf-catalyzed HMDS silylation of sugars, which can easily be integrated with subsequent reactions in one-pot fashion, has been developed. Its usefulness was demonstrated by applications to streamlined regioselectiveone-potprotection and nonenzymatic acetylation of un
Switching between <i>X</i>-Pyrano-, <i>X</i>-Furano-, and Anhydro-<i>X</i>-pyranoside Synthesis (X = C, N) under Lewis acid Catalyzed Conditions
作者:Youngran Seo、Jared M. Lowe、Neyen Romano、Michel R. Gagné
DOI:10.1021/acs.orglett.1c01713
日期:2021.8.6
A variety of C-glycosides can be obtained from the fluoroarylborane (B(C6F5)3) or silylium (R3Si+) catalyzed functionalization of 1-MeO- and per-TMS-sugars with TMS-X reagents. A one-step functionalization with a change as simple as the addition order and/or Lewis acid and TMS-X enables one to afford chiral synthons that are common (C-pyranosides), have few viable synthetic methods (C-furanosides)
各种C-糖苷可以从氟芳基硼烷(B(C 6 F 5 ) 3 )或硅基(R 3 Si + )催化的1-MeO-和全TMS-糖与TMS-X试剂的官能化获得。一步功能化只需简单地改变加成顺序和/或路易斯酸和 TMS-X,即可获得常见的手性合成子( C-吡喃糖苷),但几乎没有可行的合成方法( C-呋喃糖苷),或实际上是未知的(脱水-C-吡喃糖苷),其机械地分别由是否发生直接取代、异构化/取代或取代/异构化而产生。
New triterpenoid saponins from the roots of Platycodon grandiflorum
of the antiviral active fraction of the roots of Platycodongrandiflorum leads to the isolation of three new triterpenoid saponins, platycosides G1–G3 (1–3), as well as two known saponins, platycodin D3 (4), and platycoside E (5). The structures of the new compounds were elucidated on the basis of their spectral data and chemical evidences. The isolated saponins were tested for their antiviral activities