Glycosides deoxy, hydrolysis

A number of deoxy-, dideo y-monofluoro-, and dideoxy-difluoro-o-D-glucopyranosyl phosphates have been prepared for a comparative study of their acid hydrolysis rates. As in the hydrolysis of alkyl glycosides, deoxy derivatives reacted faster and fluorinated analogues much slower than the parent 1-phosphates, and it was concluded that the transition states for the hydrolysis of glycosides and glycosyl phosphates are essentially identical. ... 

It was of interest to determine whether glycosides of 6-deoxy-D-xylo-hex-5-enopyranose were susceptible to enzyme hydrolysis by / -glucosi-dase. Since aromatic glucosides are hydrolyzed by this enzyme at a much faster rate than aliphatic glycosides, phenyl 6-deoxy-/ -D-rt/Zo-hex-5-enopyranoside (18) was prepared (20). Phenyl / -D-glucopyranoside was converted to the 6-tosylate by selective esterification and then, by conventional procedures, transformed to phenyl 2,3,4-tri-0-acetyl-6-deoxy-... 

This section is completed with a brief review of the synthesis and properties of this epimer (20) of the precursor of thiazole in bacteria. This pentulose is conveniently accessible by an unconventional route (Scheme 19). Methyl 2,3 4,6-di-O-isopropylidene-a-D-mannopyranoside, readily available from methyl ot-D-mannopyranoside, is converted to the ketonic glycoside by butyllithium in 91% yield, following a method first published by Klemer and Rodemeyer43 and scaled up by Horton and Weckerle.44 This was converted by means of lithium hydroxide in a water-ether mixture into 3,5-0-benzylidene-l-deoxy-D-eryf/iro-2-pen-tulose in 55% yield. Hydrolysis to the free pentulose (20) proceeded in 73% yield in aqueous acetic acid. This product was obtained as a syrup with a characteristic absorption band at 1705 cm 1 as a film. Thus, there is a fair proportion of the open-chain ketone under these conditions, as with the D-threo epimer.45... 

Operculinic acids E (hexadecanoic acid, (115)-[(0-6-deoxy-a-L-mannopyranosyl-(1 4)-0-6-deoxy-a-L-mannopyranosyl-(1 4)-0-6-deoxy-a-L-mannopyranosyl-(1 2)-jS-D-glucopyranosyl)oxy]) and F (hexadecanoic acid, (115)-[(0-6-deoxy-a-L-mannopyranosyl-(1 4)-0-6-deoxy-a-L-mannopyranosyl-(1 4)-0-6-deoxy-a-L-mannopyranosyl-(1 2)-/i-D-xylopyranosyl)oxy]) were obtained by alkaline hydrolysis of the ether-soluble crude resin glycosides from the roots of Ipomoea... 

The alkaline hydrolysis of the ether-insoluble resin glycoside fraction from seeds of Ipomoea nil (L.) Roth (syn. Pharbitis nil Choisy) yielded a pentasaccharide of ipurolic acid, which was named pharbitic acid C (tetradecanoic acid, ll-[(0-6-deoxy- S-D-glucopyranosyl-(1 4)-0-6-deoxy-a-L-mannopyranosyl-(l—>6)-0-[6-deoxy-a-L-mannopyranosyl-(l—>2)-0-jS-D-glucopyranosyl-(l—>2)]- S-D-glucopyra-nosyl)oxy]-3-hydroxy). On complete hydrolysis, it produced two o-glucoses, two L-rhamnoses, one o-quinovose, and the aglycone moiety (77). 

This enzyme [EC 3.2.2.17], also known as deoxyribodi-pyrimidine endonucleosidase, catalyzes the hydrolysis of the A -glycosidic bond between the 5 -pyrimidine residue in cyclobutadipyrimidine (in the DNA) and the corresponding deoxy-D-ribose residue. 

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