Ethers, of carbohydrates

Ethers are formed under conditions of the Williamson ether synthesis Methyl ethers of carbohydrates are efficiently prepared by alkylation with methyl iodide m the presence of silver oxide... 

N HCl, EtOH, reflux, 90% yield for cholesterol. Although a direct stability comparison was not made, this group should be more stable than the THP group for the same reasons that the anomeric ethers of carbohydrates are more stable than their 2-deoxy counterparts. 

Benzyl and triphenylmethyl ethers of carbohydrates are preferred over methyl ethers when selective removal of protecting groups is important. The relatively high nucleophilic activity of the 5-hydroxyl group in glycosides and 1,2-O-alkylidene derivatives of 4 permits its benzylation and triphenylmethylation under mild conditions. Thus, treatment of 33 (Ref. 34) and 36 (Ref. 57) with benzyl bromide and... 

Photochemical Reactions of o-Nitrophenyl Ethers of Carbohydrates and Nucleosides... 

Allyl Ethers of Carbohydrate. A number of compds, such as allyl glycerol, allylglycol, allyl mannitol, allylsorbitol, all yl pent a-erythritol, etc were prepd during and after WWII by Nichols Yanovsky. They also discussed previous work on this subject and listed several refs. According to them the first compd of this type was triallyl-glycerol prepd in 1856 by M.Berthelot S. de Luca... 

Protection of hydroxyl groups Benzyl or allyl ethers of carbohydrates are obtained in satisfactory yield by reaction with 1 or 2 in cyclohexane in the presence of triflic add (20°). Trichloroacetamide precipitates and the desired ethers are obtained from the filtrate after neutralization. 

Many other ethers of carbohydrates have been prepared and described among these the more common additional ones are the following ethyl, benzyl, hydroxymethyl, hydroxyethyl, allyl, and cyanoethyl ethers. In the vast majority of the cases complete or nearly complete substitution of the hydroxyl groups was effected. In other instances partial substitution was obtained, but often little or no information was supplied concerning the location of substituents. Investigations of these types will be mentioned briefly, in order mainly to indicate the extent of the information that is available. 

There are many silylating reagents for the conversion of an alcohol into the corresponding silyl ether. The reader should consult the Handbook of the Pierce Chemical Co. for an authoritative survey. The procedure for the formation of trimethylsilyl ethers of carbohydrate derivatives with hexamethyldisilazane/ chlorotrimethylsilyl chloride in pyridine and the subsequent examination by g.l.c. analysis is described in Section 2.31. 

The use of silyl ethers of carbohydrates to alter the solubility properties is incorporated in problems. 

Helpbrich, Burckhardt, Trityl Ethers of Carbohydrates, 3,79-111 Hibbert, Harold. See Evans, Taylor H. Hindbrt, Marjorie. See Karabinos, J. 

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