Sugars benzyl ethers

The use of DDQ in dichloromethane/water for the cleavage of primary allyl and benzyl ethers has been reported, and anhydrous ferric chloride in dichloromethane debenzylated sugar benzyl ethers, without affecting acetals, benzoates, phthalimides and glycosidic linkages. 4-Methoxy- and 3,4-dimethoxy-benzyl ethers have been deprotected with catalyic DDQ and ferric chloride. The combination of Ti(0 Pr)4 and BuMgCl has been used to cleave allyl ethers to the corresponding alcohols. 

More successful applications of periodate oxidation to substituted sugars were made employing the sugar phosphates and phosphoric acids,63 66 the chloraloses, 62 70 the benzyl ethers of sugars,71 72 a dimethyleneoxy sugar,73... 

Cyclization of the bis-epoxides 123 (mixtures of diastereomers) with benzylamine afforded the azepanes 124 in a preferential 1-endo-tet methodology (Equation 17) <1995JOC5958> however, with the corresponding 3,4-benzyl ethers of the bis-epoxides rather than the // / -acetonide protecting group, no cyclization to six-membered ting species was observed. The azepanes 124 were then converted in two steps to the amino sugar hydrochloride salts 126 via the N-debenzylated intermediates 125 (Scheme 16). 

Benzyl ethers.2 Benzyl ethers of sugar alcohols can be obtained in 82-98% isolated yield by reaction with 1 and catalytic amounts of triflic acid under these conditions isopropylidene and benzylidene acetal groups are stable, as well as ester and imide groups. The reagent thus is comparable to benzyl triflate (6,44). 

In addition to benzyl ethers, various C-substituted 1,2-anhydro sugars have been described, for example pivaloyl,46 tert-butyldimethylsilyl,33,47 4,6-O-benzylidene,33 and methyl.17 The anhydro sugars just mentioned have been prepared by several synthetic routes ... 

The exocyclic 0-atoms of the sugar have to be activated before the benzyl ether is formed. 

Maher, George G., The Methyl Ethers of the Aldopentoses and of Rhamnose and Fucose, X, 257-272 Maher, George G., The Methyl Ethers of D-Galactose, X, 273-282 Manners, D. J., The Molecular Structure of Glycogens, XII, 261-298 Marsh, C. A. See Conchie, J. McCloskey, ChesterM., Benzyl Ethers of Sugars, XII, 137-156 McColloch, R. J. See Kertesz, Z. I. McDonald, Emma J., The Polyfructo-... 

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