Preparation of 1-O-Acyl-D-GlycopyranosesviaChloroacetylated Glycopyranosyl Donors

Hydroxycinnamoyl Glucose and Tartrate Esters and Their Role in the Formation of Ethylphenols in Wine

Synthesized p-coumaroyl and feruloyl l-tartrate esters were submitted to Brettanomyces bruxellensis strains AWRI 1499, AWRI 1608, and AWRI 1613 to assess their role as precursors to ethylphenols in wine. No evolution of ethylphenols was observed. Additionally, p-coumaroyl and feruloyl glucose were synthesized and submitted to B. bruxellensis AWRI 1499, which yielded both 4-ethylphenol and 4-ethylguaiacol. Unexpected chemical transformations of the hydroxycinnamoyl glucose esters during preparation were investigated to prevent these in subsequent synthetic attempts. Photoisomerization gave an isomeric mixture containing the trans-esters and undesired cis-esters, and acyl migration resulted in a mixture of the desired 1-O-β-ester and two additional migrated forms, the 2-O-α- and 6-O-α-esters. Theoretical studies indicated that the photoisomerization was facilitated by deprotonation of the phenol, and acyl migration is favored during acidic, nonaqueous handling. Preliminary LC-MS/MS studies observed the migrated hydroxycinnamoyl glucose esters in wine and allowed for identification of feruloyl glucose in red wine for the first time.

Synthesis of 5-aminopentyl mono- to tri-saccharide haptens related to the species-specific glycopeptidolipids of Mycobacterium avium-intracellulare serovars 8 and 21

The preparation of pyruvate acetal-containing 5-aminopentyl mono-, di-, and tri-saccharide fragments related to serovars 8 and 21 of the species-specific glycopeptidolipid of Mycobacterium avium-intracellulare is described. The saccharides were constructed by sequential coupling of the suitably protected 4,6-O-[(S)-1-methoxycarbonylethylidene]-D-glucopyranosyl trichloroacetimidates 6 and 7 to Z-protected 5-aminopentanol, to give the serovar 21 monosaccharide fragment 9 upon deblocking; and to ethyl 2-O-benzoyl-4-O-benzyl-1-thio-alpha-L-rhamnopyranoside (18), to give the corresponding ethyl 1-thio-disaccharides 21 and 23, respectively. Subsequent N-iodosuccinimide-promoted coupling of the latter with Z-protected 5-aminopentanol followed by deblocking of the products afforded the corresponding disaccharide fragments 26 (serovar 8) and 27 (serovar 21), respectively. Condensation of 21 with Z-protected 5-aminopentyl 3,4-di-O-benzyl-6-deoxy-alpha-L-talopyranoside (28) and subsequent deblocking of the resulting trisaccharide gave the serovar 8 fragment 5-aminopentyl O-(4,6-O-[(S)-1-carboxyethylidene]-3-O-methyl-beta-D-glucopyranosyl)- (1-->3)-O-alpha-L-rhamnopyranosyl-(1-->2)-6-deoxy-alpha-L-talopyranos ide (30).