Anhydro peracetates

SCHEME 13. Chowdhary, Hough, and Richardson s conversion of S L /l- -hexa-O-pivaloylsucrose into the 2,3-anhydro-4-chloro-talo-sucrose peracetate (1986). 

It follows from the H-n.m.r. spectra of the 1,6-anhydrohexofuranose peracetates (see Table IV) that their 1,3-dioxane ring exists in the alCa4 conformation99,113,119,121,793 and their oxolane ring favors the E0 conformation,119 although, for the D-g alacto triacetate (271), the E4 conformation of the oxolane ring was assumed.119,783 For l,6-anhydro-/3-... 

In a survey " of the behavior of various classes of carbohydrate derivatives in c.i.m.s., it was found that the principal ion is the MH (isobutane) or M -I- NH (ammonia) ion, or a simple elimination product from it. The ammonia-mediated spectra feature M -I- NH f as the major ion with simple aldoses, their acetylated methyl glycosides, 1,6-anhydro-aldohexopyranoses (and their triacetates), and acetylated 1-thioaldoses. Aldose diethyl dithioacetals show M -I- NHf — EtSH as the principal ion, whereas this ion for aldehydo-aldose peracetates is MH — AcOH. 

Anhydro-B-D-glucopyranose has been identified as a product from hydrothermolysis of cellulose and its degradation in aqueous solution at 200-240°C examined.A mild procedure for the synthesis of 1,6-anhydrohexopyranoses involves treatment of the pentabromophenyl g-glycosides (obtained in two steps from the B-peracetates) with tetrabutylammonium hydroxide at 20°C, followed by... 

An abbreviated synthesis of penta-O-acetyl-a-D-altropyranose, and hence altrose, involves treatment of methyl 2,3-anhydro-4,6-0-benzylidene-o -D-allo-pyranoside with acetic anhydride-sulphuric acid mixtures. The peracetate was obtained in 64% yield. ... 

Dehydration of 2,6-anhydro-D-heptonamlde peracetates with N-(chloromethylene)-N-methylmethanamlnium chloride affords an alternative synthesis of glycosyl cyanides as exemplified in Scheme... 

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