Pyranose

About: Pyranose is a research topic. Over the lifetime, 1619 publications have been published within this topic receiving 35348 citations. The topic is also known as: pyranoses & hexopyranose.

Synthesis of 3,7-anhydro-D-glycero-D-ido-octitol 1,5,6-trisphosphate as an IP(3) receptor ligand using a radical cyclization reaction with a vinylsilyl tether as the key step. Conformational restriction strategy using steric repulsion between adjacent bulky protecting groups on a pyranose ring

Abstract: 3,7-Anhydro-d-glycero-d-ido-octitol 1,5,6-trisphosphate (5) was designed as a novel IP3-receptor ligand having a C-glycosidic structure and was synthesized via a radical cyclization reaction with a temporary connecting vinylsilyl tether as the key step. The phenyl 2-O-dimethylvinylsilyl-3,4,6-tri-O-benzyl-1-seleno-β-d-glucopyranoside (7), in the usual 4C1-conformation, was successively treated with Bu3SnH/AIBN and under Tamao oxidation conditions to give a mixture of five C-glycosidic products. On the other hand, similar successive treatment of the corresponding 3,4-di-O-TBS-protected substrates 13 and 24, which were in an unusual 1C4-conformaion due to the steric repulsion between the bulky silyl protecting groups, gave the desired 1α-C-glycosides 18 and 25, respectively, as the major products. Thus, the course of the radical cyclization was effectively controlled by a change in the conformation of the pyranose ring into a 1C4-form due to steric repulsion between the adjacent bulky TBS-protecting groups ...

The Crystal Structure of Sucrose Sodium Bromide Dihydrate

Abstract: The complete crystal structure of sucrose sodium bromide dihydrate has been determined. The crystals are orthorhombic, with space-group P2$\_{1}$2$\_{1}$2$_{1}$, and cell-edges a = 21$\cdot $92, b = 9$\cdot $72, c = 8$\cdot $43 A. The bromine positions were obtained from Patterson-Harker syntheses, and the signs of the F's of the (0kl), (h0l) and (hk0) planes from the change of intensity from the chloride to bromide compounds. Fourier projections parallel to the three axes were used to determine the complete structure. In the structure the pyranose ring of the molecule is of the Sachse trans form. The furanose ring is an unexpectedly compact grouping, and one member of the ring is displaced from the plane of the other four. The configuration of both rings is such as to allow the groups attached to the ring atoms to approach as nearly as possible to the mean plane of each ring. Direct proof that sucrose may be described as $\alpha $-d-glucopyranosido-$\beta $-d-fructofuranoside has been obtained for the first time. The sucrose molecules are held together by bonds from the hydroxyl groups to the Na and Br ions and to the water molecules, the hydroxyl groups each having two external bonds. The method used of reducing the observed intensities to an absolute scale is described, and the proof of the correctness of the structure is given as a set of diagrams of calculated and observed electron density.

Properties of pyranose dehydrogenase purified from the litter-degrading fungus Agaricus xanthoderma.

Abstract: We purified an extracellular pyranose dehydrogenase (PDH) from the basidiomycete fungus Agaricus xanthoderma using ammonium sulfate fractionation and ion-exchange and hydrophobic interaction chroma ...

An Enantioselective Ring Expansion Route Leading to Furanose and Pyranose Nucleosides Featuring Spirodiketopiperazines at the Anomeric Position

Abstract: A study directed at the enantioselective synthesis of spirodiketopiperazine homologues of hydantocidin is described. Furanoid glycals, systems that are amenable to C-5 metalation in the presence of tert-butyllithium, are readily coupled to N-protected 2,3-azetidinediones provided that at least 1 equiv of BF3·OEt2 is present to curb enolization. The resulting 1:1 mixtures of carbinols undergo smooth ring expansion to spirocyclic keto amides when heated with pyridinium p-toluenesulfonate in benzene. 1,2-Acyl shifts operate exclusively. Since attempts to engage these products in Beckmann rearrangement proved singularly unsuccessful, recourse was alternatively made to new methodology based upon sequential Baeyer−Villiger oxidation and ammonolysis. The data show that the first of these steps occurs with exclusive migration of the quaternary carbon. Furthermore, nucleophilic attack by NH3 can be directed regioselectively to the anomeric region. If heating is supplied during acid-promoted cyclization to the spir...