Zygfryd Smiatacz

The use of tri-O-acetyl-D-glucal and -D-galactal in the synthesis of 3-acetamido-2,3-dideoxyhexopyranoses and -hexopyranosides.

Addition of hydrazoic acid to alpha,beta-unsaturated aldehydes derived from tri-O-acetyl-D-glucal and -D-galactal gave 3-azido-2,3-dideoxyhexopyranoses. These were converted into 1,4,6-tri-O-acetyl-3-azido-2,3-dideoxyhexopyranoses as well as methyl and ethyl glycosides. Hydrogenation of the proamine group in 3-azido-2,3-dideoxy derivatives provided different 3-amino and 3-acetamido sugars. The configuration and conformation of all products were established on the basis of the 1H and 13 C NMR, IR and polarimetric data.

Synthesis, X-ray structure and high-resolution NMR spectroscopy of methyl 3-azido-2,3-dideoxy-α-d-arabino-hexopyranoside

The synthesis, crystal structure data and 1H and 13C NMR spectroscopy of methyl 3-azido-2,3-dideoxy-alpha-D-arabino-hexopyranoside (5b) is reported. This compound adopts the 4C1 conformation. Hydrogen-bonded molecules of 5b form helices around the crystallographic 4(1) axis.

Configuration and conformation of the products of reaction of 3,4-di-O-acetyl-2-deoxy-2-nitroso-β-d-arabinopyranosyl chloride with pyrazole

Abstract 3,4-Di-O-acetyl-2-deoxy-2-nitroso-β- d -arabinopyranosyl chloride reacts with pyrazole in acetonitrile to afford 1-(3,4-di-O-acetyl-2-deoxy-2-hydroxyimino-α- d -erythro- and -β- d -erythro-pentopyranosyl)pyrazole, the configuration and conformation of which were established on the basis of 1H-n.m.r., polarimetric, and crystallographic data.

The synthesis of diosgenyl 2-amino-2-deoxy-β-d-glucopyranoside hydrochloride

Abstract The N -trifluoroacetyl- and N -tetrachlorophthaloyl-protected bromide of d -glucosamine has been used for the first time as a glycosyl donor for the glycosylation of diosgenin [(25 R )-spirost-5-en-3β-ol]. Both 1,3,4,6-tetra- O -acetyl-2-deoxy-2-trifluoroacetamido-β- d -glucopyranoside and 1,3,4,6-tetra- O -acetyl-2-deoxy-2-tetrachlorophthalimido-α,β- d -glucopyranoside were transformed into the appropriate glycosyl bromides. These reacted with diosgenin under mild conditions, using silver triflate as a promoter, and gave the corresponding protected diosgenyl glycosides. Each was deprotected to give diosgenyl 2-amino-2-deoxy-β- d -glucopyranoside hydrochloride. The structures of the new glycosides were established by 1 H NMR spectroscopy.

The structure and properties of the products of reaction between 3,4,6-tri-O-acetyl-2-deoxy-2-nitroso-α-d-galactopyranosyl chloride and pyrazole

Abstract Dimeric 3,4,6-tri- O -acetyl-2-deoxy-2-nitro-α- d -galactopyranosyl chloride reacts with pyrazole in acetonitrile to give 1-(3,4,6-tri- O -acetyl-2-deoxy-2-hydroxyimino-α- d - lyxo -, -β- d - lyxo -, and -β- d - xylo -hexopyranosyl)pyrazole. The stereospecificity of the reaction depends on the temperature and its duration. Transformations of the type α- d - lyxo -←β- d - lyxo α β- d - xylo have been observed. The condensation products were modified at C-2 or C-3. The following derivatives have thus been obtained: 1-(α- d -galacto-, 2-acetamido-2-deoxy-α- d -galacto-, -α- d -talo-, and -α- d - xylo -hexo-pyranosyl)pyrazole, ( Z )- and ( E )-1-(3-azido-2,3-dideoxy-2-hydroxyimino-α- and -β- d - lyxo - and -α- d - xylo -hexopyranosyl)pyrazole, 1-(3-acetamido-2-acetoxyimino-4,6-di- O -acetyl-2,3-dideoxy-α- and -β- d - lyxo -hexopyranosyl)pyrazole, as well as ( Z )- and ( E )-1-(2,3-dideoxy-2-hydroxyimino-α- d - threo -hexopyranosyl)pyrazoles.

Selective benzoylation of some N-acetyl-N-aryl-β-D-xylopyranosylamines☆

Abstract Selectivity in the benzoylation of N -acetyl- N - p -methoxyphenyl-, - p -bromophenyl-, and - p -chlorophenyl-β- D -xylopyranosylamines has been demonstrated. The structures of the products was shown by using periodate oxidation and n.m.r. spectroscopy. The relative reactivity of the hydroxyl groups was HO-3 ≈ HO-4 > HO-2. The β- D -xylopyranosylamine derivatives were shown to possess the 4 C 1 conformation.

The Synthesis and Structure of Selected Methyl (3,4-Di-O-acetyl-2-deoxy-2-hydroxyimino-d-arabino-hexopyranosid)urontes

Abstract Dimeric methyl (3,4-di-O-acetyl-2-deoxy-2-nitroso-α-d-glucopyranosyl chloride)uronate (1) reacts with nucleophiles such as: ethanol, pyrazole, methyl N-tert-butyloxycarbonyl-L-serinate to give corresponding glycosides. The stereospecifity of the glycosidation reaction depends mainly on the employed nucleophile. The configuration and conformation of the obtained glycosides were established on the basis of 1H NMR and polarimetric data, and additionally the structure of 1-(methyl 3,4-di-O-acetyl-2-deoxy-2-(Z)-hydroxyimino-α-d-arabino-hexopyranosyluronate)pyrazole (6), was supported by X-ray diffraction data.

Crystal and molecular structure of two 2-deoxy-2-hydroxyimino derivatives of β-D-arabino-hexopyranose

Abstract The crystal structure of N-acetyl-N-(3,4,6-tri-O-acetyl-2-deoxy-2-hydroxyimino-β-d-arabino-hexopyranosyl) amine (1) and 3,4,6-tri-O-acetyl-2-deoxy-2-hydroxyimino-β-d arabino-hexopyranosyl azide (2) were determined by direct methods and refined by fullmatrix least squares to a final value of R = 0.034 for 3114 (1) and 2924 (2) reflections. The pyranoid rings of both compounds have almost identical conformation between the 0S2 twist-boat and the 3,0B boat. It was found using semi-empirical quantum mechanical calculations that the conformation observed in the solid state for both compounds, similar to that in solution, is more stable than the other possible, 4C1 conformation. Similarity of geometries of 1 and 2 suggests that the pyranoid ring is less flexible than those with a chair conformation in other 2-hydroxyimino derivatives of pyranosides. On the other hand the observed conformations of 1 and 2 as well as the postulated way for acetyl group migration during hydrogenation of 2-acetoxyimino ana...

From Tri‐O‐Acetyl‐D‐Glucal to (2R,3R,5R)‐2,3‐Diazido‐5‐Hydroxycyclohexanone Oxime

Abstract Methyl 3‐azido‐2,3‐dideoxy‐α/β‐D‐arabino‐ and ‐α/β‐D‐ribo‐hexopyranosides were transformed into 6‐iodo analogues via p‐tolylsulfonyl compounds. Elimination of hydrogen iodide from 6‐iodo glycosides provided methyl 4‐O‐acetyl‐3‐azido‐2,3,6‐trideoxy‐α‐ and ‐β‐D‐threo‐hex‐5‐eno‐pyranosides or 3‐azido‐4‐O‐p‐tolylsulfonyl‐2,3,6‐trideoxy‐α‐D‐threo‐ and ‐β‐D‐erythro‐hex‐5‐eno‐pyranosides. Ferriers carbocyclization of 4‐O‐acetyl‐3‐azido‐2,3,6‐trideoxy‐α‐ and ‐β‐D‐threo‐hex‐5‐eno‐pyranosides gave (2S,3R,5R)‐2‐acetoxy‐3‐azido‐5‐hydroxycyclohexanone, which was converted into oxime. The 2‐OAc group in oxime was substituted by azide ion to yield (2R,3R,5R)‐2,3‐diazido‐5‐hydroxycyclohexanone oxime. The configuration and conformation of all products are widely discussed on the basis of the 1H and 13C NMR.

Synthesis, the crystal structure, and high-resolution NMR spectroscopy of methyl 4-O-acetyl-3-azido-2,3,6-trideoxy-6-iodo-α-d-arabino-hexopyranoside

Selective tosylation followed by acetylation of methyl 3-azido-2,3-dideoxy-alpha-D-arabino-hexopyranoside (1) in pyridine at room temperature affords a mixture of methyl 4-O-acetyl-3-azido-2,3-dideoxy-6-di-O-p-tolylsulfonyl-alpha-D-arabino-hexopyranoside (4) and methyl 3-azido-2,3-dideoxy-4,6-di-O-p-tolylsulfonyl-alpha-D-arabino-hexopyranoside (3). Compound 4 undergoes nucleophilic displacement with sodium iodide in acetic anhydride to give methyl 4-O-acetyl-3-azido-2,3,6-trideoxy-6-iodo-alpha-D-arabino-hexopyranoside (7), whose crystal structure and (1H) and (13)C NMR data are reported. This compound adopts the 4C(1) conformation.