Peter Norris

Dipolar cycloaddition reactions on a soluble polymer-supported dipolarophile: Synthesis of sugar-derived triazoles

Abstract An organic-soluble polymer-supported alkyne has been employed as a dipolarophile in 1,3-dipolar cycloaddition reactions with azides. Several carbohydrate-derived azides react to form mixtures of regioisomeric triazoles in good to high yields, and the thus formed heterocycles are freed from the polymer under mild conditions using NaBH 4 in ethanol.

Rapid Access to Glucopyranosyl-1,2,3-triazoles via Cu(I)-catalyzed Reactions in Water

1-Azido-1-deoxy-2,3,4,6-tetra-O-acetyl-β-D-glucopyranose reacts with various terminal alkynes in the presence of CuSO 4 /ascorbic acid in water to give the corresponding 1,4-disubstituted 1,2,3-triazoles, which are isolated in high yield and purity by simply filtering the precipitate from the reaction mixture. Several sugar-derived acetylenes react similarly to yield triazole-linked disaccharide analogs.

Synthesis of 1,5-dideoxy-1,5-imino-d-xylonolactam VIA acid-catalyzed intramolecular schmidt rearrangement

Summary 5-Azido-2,3,4-tri- O -benzoyl-5-deoxy-D-xylose diethyl dithioacetal (3) undergoes smooth Lewis acid-catalyzed demercaptalation (boron trifluoride etherate/HgO) to afford the unstable aldehydo -azide 4 , which in the presence of Lewis acids yields the tribenzoate 6 of the title compound ( 7 ) via an apparent intramolecular Schmidt rearrangement.

A convenient synthesis of glycosyl chlorides from sugar hemiacetals using triphosgene as the chlorine source

Treating partially protected sugar hemiacetals with triphosgene in THF results in the formation of glycosyl chlorides. The method is compatible with acid-sensitive isopropylidene protecting groups in the hemiacetal substrates.

Intramolecular carbene and nitrene insertions at C-2 of diacetone-D-glucose

Abstract Decomposition of a diazoester and an azidoformate attached at O-3 of 1,2;5,6-di- O -isopropylidene- d -glucofuranose (‘diacetone- d -glucose’) leads to intramolecular insertion into the C-2H bond as the major process in both cases.

Cu(I)-catalyzed Formation of D-Mannofuranosyl 1,4-Disubstituted 1,2,3-Triazolecarbohybrids

2,3:5,6-Di-O-isopropylidene-D-mannofuranose has been exploited as a platform for the synthesis of new 1,2,3-triazolecarbohybrids. Placement of an azide group at C-1 (and C-6) of the carbohydrate allows for reaction with various alkynes in the presence of a Cu(I) catalyst to generate 1,4-disubstituted triazoles regiospecifically. The use of sugar-derived alkynes leads to 1,2,3-triazole-linked di- and trisaccharide carbohybrid analogs with retention of the β-D-manno configuration.

Crystal structure of methyl 1,2,3,4-tetra-O-acetyl-β-d-glucopyranuronate

Abstract The identity of the crystalline product formed by the acetylation of a mixture of methyl α- and β- d -glucopyranuronates has been confirmed as being methyl 1,2,3,4-tetra- O -acetyl-β- d -glucopyranuronate ( 3 ), which agrees with the assignment from 1 H NMR. The absolute configuration of compound 3 was assigned to agree with the known chirality of the precursor sugar, d -glucono-6,3-lactone.

2,3,4,6‐Tetra‐O‐acetyl‐β‐d‐gluco­pyran­osyl azide

The structure of the title compound, C14H19N3O9, has been determined at 100 K. The six-membered ring exhibits a chair conformation, and all non-H substituents are found in equatorial positions.

Intramolecular 1,3-dipolar cycloadditions of 5-azido-5-deoxyaldopentose ketene dithioacetal bis(sulfones) in the synthesis of imino sugar analogs

Abstract Oxidation of the dithioacetal groups in the O -acetylated 5-azido-5-deoxy dibenzyl dithioacetal 3 of D-xylose and that ( 7 ) of D-ribose leads to triazoline derivatives 4 and 8 , the products of sequential oxidation to the bis(sulfones), loss of AcOH between C-1 and C-2 and, spontaneous intramolecular 1,3-dipolar cycloaddition of an azido ketene intermediate. A possible explanation of the observed diastereoselectivity is discussed.

Azidonitration of Di-O-acetyl-L-fucal: X-Ray Crystal Structures of Intermediate Azidodeoxysugars and of the Bacterial Aminosugar N-Acetyl-L-fucosamine

The azidonitration of di-O-acetyl-l-fucal has previously been shown to be an efficient route to the bacterial aminosugar N-acetyl-l-fucosamine. Upon repeating this sequence, with updated versions of the glycal formation and amide installation steps, we have obtained X-ray crystal structures of several of the addition products, which are now reported along with the solid-state structure of N-acetyl-l-fucosamine itself.