Glucopyranose displacement reactions

Sulphonate displacement reactions have been used to introduce nitrogen functionality. 2-Amino-2-deoxy-D-arabinose has been synthesized in two related nine-step procedures from methyl 3, - -Isopropylldene-D-arablnopyranoside, involving reaction of a 2- -tosyl-D-rlboside with either azide ion or hydrazine. A variety of 1,6-anhydro-2-azido-2-deoxy-6-D-glucopyranose derivatives, of potential as glucosamine monomers in oligosaccharide synthesis, have been obtained from the corresponding 1,6-anhydro-D-mannose 2-trl-... 

Reaction of the photobromination product 40 of tri-<9-acetyl-1,6-anhy-dro-/ -D-glucopyranose under conditions of kinetic control gives mainly the c rfo-products of displacement with inversion of configuration thus, potassium thiophenolate affords compound 142 in 73% yield, and methanolysis... 

As expected on the basis of the epoxy halide results just discussed, die displacement of a primary tosyl-ate can be smoothly accomplished in the presence of an adjacent disubstituted epoxide,and this reaction has been utilized in syntheses of disparlure and of other insect pheromones. On the other hand, a recently reported reaction of a cyclic glucopyranose-derived epoxide with either Me2CuLi or MeMgCl-CuBr afforded in high yield the desired ring-opened product, leaving intact an exocyclic primary mesylate. 

The introduction of an amino-group into carbohydrates has been achieved by displacement of a tosyloxy or similar leaving group by participation of a neighbouring 0-carbamoyl group (—CONHR). Thus, 2-amino-l,6-anhydro-2-deoxy-j3-D-mannose was prepared from 1,6 3,4-dianhydro-2-0-tosyl- 8-D-glucopyranose as outlined in Scheme 1. A similar reaction has been proposed by Barton and Motherwell/ ... 

Cytidine has been converted into l-(5-amino-5-deoxy-j8-D-arabinofuranosyl) cytosine by a sequence of reactions involving A-benzoylation, sulphonation, acetylation, displacement with azide ion, e/c., and l-(3-amino-3-deoxy-jS-D-arabinofuranosyl)-6-azauracil was derived from 2, 3 -di-0-methanesulphonyl-5 -O-trityl-6-azauridine via 2,2 - and 2, 3 -anhydro-nucleosides. Other syntheses have been accomplished by the condensation of an appropriately derivatized amino-sugar with either a pyrimidine or purine derivative for example, the Hilbert route was used to prepare l-(2-amino-2-deoxy-a-D-arabino- and -jS-o-xylo-furanosyl)cytosine. > The reactivity of l,3,4,6-tetra-0-acetyl-2-acyl-amido-2-deoxy-j3-D-glucopyranoses in condensation reactions with 2,6-dichloro-purine, theophylline, and 6-benzylaminopurine was shown to be in the order benzamido > acetamido > phthalimido. 9-(3-Acetamido-2,5-di-0-acetyl-3-deoxy-j8-D-ribofuranosyl)-2,6-dichloropurine has been synthesized and converted into the corresponding 2,6-diamino- and 6-amino-2-chloro(fluoro)-nucleosides. ... 

The iodo group of l,2-isopropylidene-5-iodo-6-0-tiityl a-D-glucofiiranoside can also be displaced by thioacetate to form the 5-acetylthio derivative [114]. After the removal of the protecting groups, 5-deoxy-5-thio-D-glucopyranose is obtained (reaction 4.121). 

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