Pyranose derivatives gluco

A comparison of the three binary copolymerizations of 1,6-anhydro-/S-D-gluco-, -galacto-, and -manno-pyranose derivatives gives some insight into the mechanism of copolymerization, if it is assumed on this evidence that the per-p-xylyl and perbenzyl derivatives can be used interchangeably.107... 

Special attention was given to the conformations about the C-5-C-6 bond in semiempirical quantum mechanical nuclear shielding calculations on a series of hexopyranoses," and in molecular mechanics simulations of methyl a- and P-d-gluco-, -galacto-, and talo-pyranoside in aqueous solution," " as well as to the conformation of the acetamido group in 2-acetamido-2-deoxy-D-allo- and -d-gluco-pyranose derivatives, such as 18-20." ... 

The optical purities obtained were generally low (<40%). The acid-catalysed reaction of 6-deoxy-l,2-0-isopropylidene-3-0-methyl-a-D-xy/o-hexofuranos-5-ulose 5-(toluene-p-sulphonylhydrazone) (433) with methyl phenylphosphonite has been used in a novel method for the synthesis D-gluco- and L-ido-pyranose derivatives containing a phosphorus atmn in the hemiacetal ring (Scheme 78). ... 

Glucose isomerase has been employed to convert D-gluco- and L-ido-fiiranose derivatives 47 into D-fiucto- and L-sorbo-pyranose derivatives 48, respectively, in 70 - 80% yield, as shown in Scheme 11. p-D-Pructofuranose has been found to bind to DNA preferentially, allegedly by three hydrogen bonds to phosphate. DNA thus moves the equilibrium p-D-fructofiiranose a-D-fhictofuranose to the right ... 

The stereoselectivity of formation of l,2-dideoxy-l,2-dihalogeno-a-D-gluco-pyranose derivatives when bromine and chlorine are added to 3,4,6-tri-O-acetyl-and 3,4,6-tri-O-benzyl-D-glucal has been shown to be influenced both by the substituents and the polarity of the solvent. Similar results were observed for halogenomethoxylations. 

Uchida and co-workers have further exemplified their synthesis (cf. Vol.28, p.233) of cyclic isoureas, e.g. S a-carbatrehazolin 39, by condensing glycosyl isothiocyanates with the cyclitolamine trehazoline, and cyclizing the resulting thiourea adducts (with HgO) for further details see Chapter 19. cis-Fused 1,2-oxazolidine-2-thiones such as 40 were the exclusive products from reactions of 1,2-O-sulfinyl-a-D-gluco-furanose or -pyranose derivatives (i.e. 1,2-cyclic sulfites) with sodium thiocyanate. ... 

The inclusion complexes of 3-R 4-R2-disubstituted l,2,5-oxadiazole-2-oxide with polycyclic derivatives of gluco-pyranose were prepared by heating an aqueous ethanolic solution of /3-cyclodedextrin with the corresponding furazan... 

Anhydro sugar derivatives that have the two reacting groups held in the required anti-periplanar (diaxial) orientation afford oxi-ranes very readily. Thus, l,6-anhydro-2-0-p-tolylsulfonyl-/3-D-gluco-pyranose (3) yields l,6 2,3-dianhydro-/3-D-mannopyranose (4) within... 

Other epoxy derivatives of pyranose sugars do not show any regularity in the direction of scission. Methyl 2,3-anhydro-4,6-di-0-methyl-/3-n-mannopyranoside reacts with ammonia to afford predominantly the product with the D-altro configuration, but with sodium methoxide equal amounts of T>-altro and D-gluco isomers are obtained.No useful rules could be formulated to predict the direction of opening of epoxides by acidic reagents. ... 

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