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Title: Reactions of pyranosyl nitrile oxides : 1,3-nucleophilic addition reactions in the synthesis of novel C-glycosides
Author: Smellie, Iain Archie Sneddon
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2005
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1,3-Nucleophilic addition reactions of thiols and amines with pyranosylnitrile oxides have been employed in the synthesis of C-glycosides. The nitrile oxides were generated by base-induced dehydrochlorination of the corresponding hydroximoyl chlorides 106 and 107. D-Glucose derived hydroximoyl chloride 107 was prepared in four steps from D-glucose and employed in collaborative work toward the synthesis of glucosinolate analogue. Reaction of alkyl and aryl thiols with D-xylose nitrile oxide 151 afforded a series of desulfoisoglucosinolates in 55-76% yields. Reactions of allyl and aryl amines with the D-xylose and D-glucose derived nitrile oxides 151 and 115 under basic conditions afforded the corresponding Z-amidoximes. For example, (Z)-N-benzyl-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl)formamide oxime (137) was prepared from 107 and benzylamine in 88% yield. The addition of amino acid derived nucleophiles was also investigated Reaction of the D-xylose and D-glucose nitrile oxides 115 with L-cysteine derivatives 147 under basic conditions afforded thiohydroximates 148 and 150 in high yield. Reaction of the D-xylose nitrile oxide 151 with glycine, L-leucine and L-phenylalanine esters initially afforded amidoximes 152, 155 and 161. Cyclisation of 152, 155 and 161 to form 1,2,4-oxadiazin-6-ones occurred on exposure to silica or prolonged standing. Employing L-proline benzyl ester as the nucleophile led to the formation of predominantly oxadiazinone 163. Attempts to synthesis pyranosyl-1,2,4-oxathiazin-6-ones were not successful 6-Amino-6-deoxy-1,2,3,4-di-O-isopropylidene-α-D-galactopyranose hydrochloride was prepared from D-galactose in 4 steps, and reaction with D-xylose and D-glucose derived nitrile oxides 151 and 115 afforded (1→6) amidoxime linked pseudo-disaccharides 178 (81%) and 181 (75%) D-Xylose and D-glucose amines 182 and 183 were prepared from the parent aldoses in 5 steps. Reaction of these amines with D-xylose and D-glucose nitrile oxides 151 and 115 yielded a series of (1→1) amidoxime linked pseudo-disaccharides (41-49% yields).
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available