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A number of modifications of the original Grignard C 1 homologation of hexoses was examined, e.g. reactions of protected hexodialdo-1,5-pyranosides with benzyloxymethyllithium, transmetalation, precomplexation of the aldehydes. Some of the modifications, e.g. benzyloxymethyl Grignard addition in the presence of tert amines showed good to very good stereoselectivity of the heptoside formation.

A four-step procedure for homologation of methyl α- d - manno furanoside and α- d - manno pyranoside was examined. The reactions consisted in (i) oxidation of the terminal hydroxymethyl group in a protected sugar derivative to an aldehyde; (ii) reaction with allyloxymethylmagnesium chloride (or (phenyldimethyl)silylmethyl–magnesium chloride); (iii) protection of the newly formed secondary alcohol group; (iv) deprotection of the terminal CH 2 OR (or oxidation of the CH 2 SiMe 2 Ph) group. From methyl α- d -mannosides, stereoisomeric d α d and l α d methyl heptosides and from them, methyl octosides of d - threo - and l - erythro -α- d - manno configuration were obtained.

Three methyl 2,3,4-tri-O-acetyl-α-D-hexopyranosides of the manno, gluco, and galacto configuration were oxidized to the corresponding methyl hexodialdo-1,5-pyranosides and then reacted with allyloxymethylmagnesium chloride. Methyl heptopyranosides of the D- and L-glycero-α-D-manno-, -α-D-gluco, and -α-D-galacto configuration were obtained in moderate yields. Migration of the 4-O-acetyl group in the products was observed. An interpretation of the results was proposed.

Three O -isopropylidene group-protected pentose aldehydes (methyl 2,3- O -isopropylidene-β- d - ribo -pentodialdo-1,4-furanoside ( 1 ), methyl 2,3- O -isopropylidene-α- d - lyxo -pentodialdo-1,4-furanoside ( 2 ), and 3- O -benzyl-1,2- O -isopropylidene-α- d - xylo -pentodialdo-1,4-furanose ( 3 )) were treated at −30 °C with lithium diisopropylamide (LDA) and the mixtures obtained were reduced with LiAlH 4 . The products, obtained in moderate yields, proved that deacetonation occurred followed by aldol reactions between aldehydes 1 – 3 and acetone.

Methyl β-d-glucopyranoside reacted with a 4-molar excess of the Mitsunobu reagents (triphenylphosphine–diethyl azodicarboxylate–benzoic acid) under Weinges et al. [Carbohydr. Res., 164 (1987) 453–458] conditions to furnish four differently benzoylated methyl β-d-allopyranosides in a very good overall yield. The same reaction applied to methyl α-d-glucopyranoside yielded allosides in a low yield and nine other sugar products. These results give an insight into the course of the Mitsunobu esterification–inversion reaction.

Derivatives of four stereoisomeric pentodialdo-1,4-furanoses were reacted with four Grignard C 1 reagents: methoxymethyl-, allyloxymethyl-, benzyloxymethyl, and dimethylphenylsilylmethyl-magnesium chlorides. Derivatives of the expected stereoisomeric hexoses were accompanied in some cases by C-4 inverted products. The results have been discussed in terms of α- and β-chelated transition states. It has been found that the RX (X=O,Si) grouping of the Grignard reagent strongly influences the stereochemical outcome of the elongation reaction.

Two epimers of (+)-castanospermine, (1S,6S,7R,8R,8aS)-1,6,7,8-tetrahydroxyindolizidine [(+)-8a-epi-castanospermine] (4) and (1R,6S,7R,8R,8aS) derivative [(+)-1,8a-di-epi-castanospermine] (5) were synthesized from methyl α-D-glucopyranoside.

Synthesis of the title trisaccharide was accomplished by sugar chain extension starting from the non-reducing terminus: coupling of Glc p NAc with ld -Hep p , then adding Glc p -OAll. An alternative route started from the reducing end: coupling of ld -Hep p with Glc p -OAll, then addition of Glc p NAc. In the synthesis of the title disaccharide a modification of the first approach was employed. The allyl glycosides were coupled with cysteamine, activated with thiophosgene and conjugated to bovine serum albumin (BSA). The neoglycoconjugates obtained were used in immunochemical studies of monoclonal and polyclonal antibodies directed against Escherichia coli K-12 lipopolysaccharide.

(Phenylthio)acetyliron complex 3 was obtained by reaction of the anion generated with butyllithium from acetyliron complex 4 with diphenyl disulphide. Alkylation and aldol reactions of the anion of 3 were investigated. X-Ray structural determination of four aldols and reactions with aldehydes in the presence of Et2Al+ or Sn2+ permitted the assignment of configuration to all aldols.

From suitably protected methyl α - d -mannopyranosides five methyl l - glycero - α - d - manno -heptopyranosides were synthesized by the one-carbon-atom chain elongation at C-6 and converted to five monophosphates ( 1–5 ) having the PO(OH) 2 group at O-2, -3, -4, -6 and -7. Compounds 1–5 were exposed to acidic and basic hydrolytic conditions used in lipopolysaccharide analysis and the products and their proportion were determined. Under acidic conditions, besides hydrolysis of the glycoside, migrations and hydrolytic cleavage of the phosphate residue were found. Under basic conditions the phosphates were stable.

Methoxymercuration of α, β-unsaturated ketoester 5 (readily obtained from peracetylated D-gluconic acid 1 via Barton ester) led to a separable mixture of KDO derivative 9 and its D-gluco isomer 10.

Propargylation of pentofuranose aldehydes by treatment with propargyl bromide in the presence of zinc dust yielded homopropargylic alcohols with a good isolated yield and, in many cases, excellent anti/syn selectivity. Catalytic hydrogenation of the triple bond afforded homoallylic alcohols, valuable substrates for the synthesis of 6-deoxyheptoses. Direct ozonolysis of the triple bond yielded uronic acid esters.

The absolute configuration of the acyclic side chain of heptopyranosides and heptofuranosides was determined by exciton coupled CD, employing the strongly fluorescent 2-anthroate chromophore. The usage of this chromophore offers significant improvements over previous chemical and spectroscopic procedures since its intense fluorescence greatly facilitates the isolation and HPLC purification at the nanogram scale. The large amplitudes of the bisignate spectra allow CD manipulations in the 1 x 10(-7) M range.

The air stable (methylthio)acetyliron complex 4 was obtained by methylthiolation with dimethyldisulphide of the anion generated from acetyliron complex 1 with butyllithium. Alkylthiolation could not be achieved with a number of thiolating reagents 5–11. The enolate generated from 4 reacted readily and with high stereoselectivity with alkyl halides and with aldehydes. X-ray structural determination confirmed the pseudo-octahedral structure of 4. Decomplexation of benzylation products 16a and of aldol 18f yielded several products, the majority of them without sulphur atoms.

Deuteration and alkylation of the acyl ligand in (η5-C5H5)Fe(CO)(PPh3)(COCH2Ph) (2) led to mixtures of the diastereomeric products, and the diastereomeric proportions varied with the base used for deprotonation of 2 at −78°C. When alkylation was performed at +16°C, the results of alkylation were similar, irrespective of the base used for deprotonation. The effect of experimental conditions on the stereochemical results of these reactions was also studied. Reactions of 2 with acetaldehyde and benzaldehyde were practically non-stereoselective and the diastereomeric proportions of the products were influenced by bases employed for deprotonation. Tin dichloride or diethylaluminum chloride promoted the predominant formation of single stereoisomers. The reaction of 2 with acetone was similar to its alkylation at −78°C. Decomplexation of alkylation products with NBS resulted in bromides, and decomplexation of aldol product 11 led to mixtures of stereomeric epoxides and bromides. Decomplexation was connected with decarbonylation of the acyl ligand.

From suitably protected benzyl α- d -mannopyranosides, five benzyl l -glycero-α- d -manno-heptopyranosides were synthesized by chain-elongation at C-6. By regiospecific protection-deprotection procedures five O-benzylated heptosides having ‘isolated’ free OH groups at C-2, C-3, C-4, C-6, or C-7 were obtained. These substrates were phosphorylated and the products were converted into free monophosphates or monophosphate cyclohexylammonium salts (1–5) which were characterized by 1H, 13C, and 31P NMR spectra and high-performance anion-exchange chromatography.

The in situ complexes of [Mo 2 (OAc) 4 ] with vic-diols obtained from monosaccharides gave CD spectra suitable for determination of absolute configuration in this group. Positive (negative) torsional angle in the OCCO moiety leads to a positive (negative) Cotton effect at around 300 nm. This rule was also extended to vic-diols containing an amino group in the same molecule. Protection of the amino group as a carbamate inhibits the formation of a chiral complex with the NH 2 moiety and enables determination of absolute configuration of the diol fragment.

Summary Structural studies of two lipopolysaccharides (LPS) isolated from Rhizobium leguminosarum bv.trifolii strain 24 (giving effective symbiosis with clover) and the exo− mutant AR20 showing non-effective nodulation, were performed using conventional techniques (chemical analysis, gas chromatography (GC), methylation analysis, combined gas chromatography/mass spectrometry (GC-MS)) and NMR.The two LPS preparations contained: L-rhamnose, 6-deoxy-L-talose (dTal), D-mannose, D-galactose, D-glucose, 3-deoxy-2-heptulosaric acid (DHA) and 2-keto-3-deoxyoctonate (KDO) as major sugar components, as well as a 2,3-di-O-methylhexose, a 2,6-dideoxy-2-amino-hexose, D-glucosamine and glucosaminic acid as minor constituents.D-galacturonic acid (GalA), however, was found only in the preparation from the wild-type strain 24.All neutral hexoses and 6-deoxyhexoses have been identified as α-linked anomers. The detailed elucidation of two trisaccharide, derived from the exo− mutant AR20, namely α-L-dTalp(l→2)α-L-Rhap(l→5)DHA and α-D-Galp(l→5)α-D-Manp(l→6)KDO by methylation analysis and NMR techniques will be presented.Furthermore, the overall structure of the LPS of the wild-type strain 24 will be proposed

Syntheses of two derivatives of two 2,4-diamino-2,4,6-trideoxyhexoses having the d -gulo (16) and l -altro (29) configuration have been described. Derivative 16 was obtained by two routes starting from benzyl 2-benzyloxycarbonylamino-2-deoxy-α- d -glucopyranoside. Derivative 29 was obtained from 3,4-di-O-acetyl-l-rhamnal in a 10-step reaction sequence.

Fragmentation patterns under electron impact of selected (η5-cyclopentadienyl)dicarbonylacyliron complexes were studied. Fragmentation pathways were confirmed using accurate mass measurements and B/E = constant and mass-analysed ion kinetic energy fragment ion spectra.

Aldol reactions of sugar aldehydes (5 – 13) with enolate 2 of racemic and both enantiomeric forms of acetyliron were investigated. The steric course of reactions depended strongly on the counterions used. High stereocontrol was achieved with the following cations: tin(II), diethylaluminum(I), zirconium(IV) and the triethylaluminum-containing cation. Matched pairs, particularly with the pentose- and hexose-derived aldehydes, yielded the corresponding aldol products with very high stereoselectivities. Products of aldol reactions were decomplexed with N-bromosuccinimide in methanol. From aldols 14a-d – 18a-d stereoisomeric methyl 2-deoxypentonates and 2-deoxyhexonates were obtained and their configuration was determined. Aldols obtained from acetyliron anion (2) and pentose- and hexose-derived aldehydes 8 – 13 led after decomplexation to pairs of stereoisomeric methyl 6-deoxy(7-deoxy)-hept(oct)uronates. These products were separated and their configuration was assigned on the basis of chemical transformations to free 6-deoxyheptoses. In case of D- and L-arabino aldehydes (9 and 10)-because of low stability of products - the configuration was assigned by the synthesis of a model compound. A regularity was found in the 1H NMR spectra of methyl 6-deoxy-hepturonates connecting coupling constants Jα,β and Jα′,β of the methylene protons with the configuration of the β-carbon atom.

Treatment of racemic binaphthol (1) with neomenthylthioacetic acid chloride (2) gave monoesters 7 and 8. Their separation by column chromatography followed by reduction afforded enantiomerically pure binaphthols.

Benzyl 2,3- O -isopropylidene-4- O - p -methoxybenzyl-α- d -mannopyranoside was oxidized according to Swern, and the aldehyde obtained was treated with allyloxymethylmagnesium chloride to yield the title heptose derivative ( 7 ) as the main product. This compound had the hydroxyl group at C-6 free. Benzylation yielded the fully protected derivative 9 . O -Deallylation furnished a heptose derivative ( 10 ) having the C-7 hydroxyl group free. Similarly, removal of the p -methoxybenzyl group from 9 led to a derivative ( 11 ) with the C-4 hydroxyl group free. Acid hydrolysis of 9 under controlled conditions led to 2,3-diol ( 12 ). This compound was benzylated under two-phase conditions to yield the 2- O -benzylated product ( 13 ) having a free OH group at C-3. Benzylation of the stannylene derivative obtained from the 2,3-diol and dibutyltin oxide gave the 3- O -benzyl derivative ( 14 ) with HO-2 free. The yields of all steps are good to very good.

Synthesis of the title oligosaccharides was performed with the use of peracetylated l - glycero -β- d - manno -heptosyl trichloroacetimidate as the heptosyl donor and (oligo)glucosyl acceptors bearing acyl and acetal protecting groups.

Glycosyl thiocyanates having hydroxyl groups protected with acetyl or benzoyl groups react readily at −40°C with Grignard reagents to afford the corresponding alkyl or aryl thioglycosides in good yields. Monosaccharide derivatives having the SCN grouping at other positions form under similar conditions thioethers. Axial thiocyanates do not react. Elevated temperatures induce side reactions leading to mercaptans.

Methyl 6-deoxy-2,3-O-isopropylidene-α- d -manno-heptofuranoside (9) has been synthesised from the acetyliron complex 2 by a sequence of reactions involving deprotonation of 2, its reaction with aldehyde 5, decomplexation, isolation of 7, and reduction to 9. Compound 9 crystallises in the orthorhombic system, space group P212121, with cell dimensions: a = 6.097(1), b = 7.942(1), c = 26.862(3) A. The intensity data were collected with a Syntex P21 diffractometer. The structure was solved by direct methods and refined by the full-matrix, least-squares procedure, resulting in R = 0.049. The furanoside and 2,3-O-isopropylidene rings are characterised by envelop conformations 5E and E3, respectively. Relatively strong intermolecular hydrogen bonss were observed in the crystal structure.

The effect of replacement of triphenylphosphine in CpFe(CO)PPh3(COR) by methyldiphenylphosphine on the reactivity of the acyl ligand attached to Fe has been investigated. Reactions of anions generated from complexes (η5-C5H5) Fe(CO)(CH3PPh2)COCH3 (5) and(η5-C5H5)Fe(CO)(CH3PPh2)COC2H5 (6) with a variety of electrophilic reagents gave mixtures of diastereo- and regio-isomeric products. The proportion of these was found to be independent of the type of base used for deprotonation but dependent on the stoichiometric base-to-complex ratio. The product of benzylation 12 gave methyl 3-phenylpropionate after decomplexation with NBS in methanol.

Heptofuranose derivatives 1–6 having free 1, 3-diol systems form in situ complexes with Mo2(OAc)4 whose CD spectra permit the assignment of absolute configuration at C-5 using a sector rule proposed by G. Snatzke.2–6 The interpretation of CD spectra of analogous complexes formed from derivatives 7–12 was more complicated and did not lead to direct configuralional conclusions. CD spectra of complexes formed from Rh2(CF3COO)4 and sugar derivatives 13–21, containing an “isolated” hydroxyl group, permit the assignment of absolute configuration. Conclusions were corroborated by the investigation of CD spectra of rhodium complexes with compounds 22–27.

Conformational analysis of the alkylation and aldol condensation products of phenylacetyliron complex (4), based on1H-NMR chemical shifts and1H-1H vicinal coupling constants, permitted the assignment of relative configurations to all products obtained. Configurations and conformations of two aldol condensation products,12A and13F, were determined by X-ray structural analysis and were compared with the structures deduced from1H-NMR data. The crystals of12A and13F are monoclinic, space group of12A isP21/n with cell dimensions:a=10.937(2),b=17.278(5),c=16.412(3)A, andβ=107.52(2)°; space group of13F isP21/c, with cell dimensions:a=11.576(4),b=21.180(2),c=11.854(4)A, andβ=99.80(3)°. Both structures were solved by direct methods, and refined by a full-matrix, least-squares procedure giving for12AR=0.0599 and for13FR=0.0459.

A synthesis of tunicamine, the eleven-carbon atom sugar component of tunicamycin antibiotics, was described. The synthesis started from a derivative of 2-azido-2-deoxy-D-galactose ( 11 ) which was condensed with a furfuryl alcohol moiety. Achmatowicz-type transformation of this moiety to allo furanose system yielded a derivative of tunicamine. The synthesis required 11 steps and yielded 27 in 5.4% yield (from 11 ) and with good stereoselectivity.

Glycosyl thiocyanates having hydroxyl groups protected with acetyl or benzoyl groups react readily at −40°C with Grignard reagents to afford the corresponding alkyl or aryl thioglycosides in good yields. Monosaccharide derivatives having the SCN grouping at other positions form under similar conditions thioethers. Axial thiocyanates do not react. Elevated temperatures induce side reactions leading to mercaptans.

Methyl 6-deoxy-2,3-O-isopropylidene-α- d -manno-heptofuranoside (9) has been synthesised from the acetyliron complex 2 by a sequence of reactions involving deprotonation of 2, its reaction with aldehyde 5, decomplexation, isolation of 7, and reduction to 9. Compound 9 crystallises in the orthorhombic system, space group P212121, with cell dimensions: a = 6.097(1), b = 7.942(1), c = 26.862(3) A. The intensity data were collected with a Syntex P21 diffractometer. The structure was solved by direct methods and refined by the full-matrix, least-squares procedure, resulting in R = 0.049. The furanoside and 2,3-O-isopropylidene rings are characterised by envelop conformations 5E and E3, respectively. Relatively strong intermolecular hydrogen bonss were observed in the crystal structure.

Treatment of racemic binaphthol (1) with neomenthylthioacetic acid chloride (2) gave monoesters 7 and 8. Their separation by column chromatography followed by reduction afforded enantiomerically pure binaphthols.

Aldol reactions of sugar aldehydes (5 – 13) with enolate 2 of racemic and both enantiomeric forms of acetyliron were investigated. The steric course of reactions depended strongly on the counterions used. High stereocontrol was achieved with the following cations: tin(II), diethylaluminum(I), zirconium(IV) and the triethylaluminum-containing cation. Matched pairs, particularly with the pentose- and hexose-derived aldehydes, yielded the corresponding aldol products with very high stereoselectivities. Products of aldol reactions were decomplexed with N-bromosuccinimide in methanol. From aldols 14a-d – 18a-d stereoisomeric methyl 2-deoxypentonates and 2-deoxyhexonates were obtained and their configuration was determined. Aldols obtained from acetyliron anion (2) and pentose- and hexose-derived aldehydes 8 – 13 led after decomplexation to pairs of stereoisomeric methyl 6-deoxy(7-deoxy)-hept(oct)uronates. These products were separated and their configuration was assigned on the basis of chemical transformations to free 6-deoxyheptoses. In case of D- and L-arabino aldehydes (9 and 10)-because of low stability of products - the configuration was assigned by the synthesis of a model compound. A regularity was found in the 1H NMR spectra of methyl 6-deoxy-hepturonates connecting coupling constants Jα,β and Jα′,β of the methylene protons with the configuration of the β-carbon atom.

Methoxymercuration of α, β-unsaturated ketoester 5 (readily obtained from peracetylated D-gluconic acid 1 via Barton ester) led to a separable mixture of KDO derivative 9 and its D-gluco isomer 10.

Methyl l -glycero-α- d -manno- and d -glycero-α- d -manno-heptofuranosides (1 and 2) have been synthesized using two-carbon-atom elongation of a lyxofuranoside system. A new method for the synthesis of 2 has been developed based on the reaction of protected methyl α- d -manno-hexodialdo-1,4-furanoside with benzyloxymethylmagnesium chloride.

Synthesis of the title trisaccharide was accomplished by sugar chain extension starting from the non-reducing terminus: coupling of Glc p NAc with ld -Hep p , then adding Glc p -OAll. An alternative route started from the reducing end: coupling of ld -Hep p with Glc p -OAll, then addition of Glc p NAc. In the synthesis of the title disaccharide a modification of the first approach was employed. The allyl glycosides were coupled with cysteamine, activated with thiophosgene and conjugated to bovine serum albumin (BSA). The neoglycoconjugates obtained were used in immunochemical studies of monoclonal and polyclonal antibodies directed against Escherichia coli K-12 lipopolysaccharide.

Methyl β-d-glucopyranoside reacted with a 4-molar excess of the Mitsunobu reagents (triphenylphosphine–diethyl azodicarboxylate–benzoic acid) under Weinges et al. [Carbohydr. Res., 164 (1987) 453–458] conditions to furnish four differently benzoylated methyl β-d-allopyranosides in a very good overall yield. The same reaction applied to methyl α-d-glucopyranoside yielded allosides in a low yield and nine other sugar products. These results give an insight into the course of the Mitsunobu esterification–inversion reaction.

Three O -isopropylidene group-protected pentose aldehydes (methyl 2,3- O -isopropylidene-β- d - ribo -pentodialdo-1,4-furanoside ( 1 ), methyl 2,3- O -isopropylidene-α- d - lyxo -pentodialdo-1,4-furanoside ( 2 ), and 3- O -benzyl-1,2- O -isopropylidene-α- d - xylo -pentodialdo-1,4-furanose ( 3 )) were treated at −30 °C with lithium diisopropylamide (LDA) and the mixtures obtained were reduced with LiAlH 4 . The products, obtained in moderate yields, proved that deacetonation occurred followed by aldol reactions between aldehydes 1 – 3 and acetone.

A four-step procedure for homologation of methyl α- d - manno furanoside and α- d - manno pyranoside was examined. The reactions consisted in (i) oxidation of the terminal hydroxymethyl group in a protected sugar derivative to an aldehyde; (ii) reaction with allyloxymethylmagnesium chloride (or (phenyldimethyl)silylmethyl–magnesium chloride); (iii) protection of the newly formed secondary alcohol group; (iv) deprotection of the terminal CH 2 OR (or oxidation of the CH 2 SiMe 2 Ph) group. From methyl α- d -mannosides, stereoisomeric d α d and l α d methyl heptosides and from them, methyl octosides of d - threo - and l - erythro -α- d - manno configuration were obtained.

The title compounds were synthesised, and appropriate derivatives were characterised by GLC, GLC-MS, and NMR spectroscopy. The GLC and GLC-MS data proved 2-O-(6-O-L-glycero-alpha-D-manno-heptopyranosyl-alpha-D-glucopyranosyl)- D- glucopyranose to be a constituent of the outer-core region of the lipopolysaccharide from Escherichia coli K-12, indicating the heptosyl residue to be linked to the terminal glucopyranose residue.

Three approaches to the synthesis of deaminotunicamine and derivatives were developed. Tin tetrachloride condensation of 6-deoxy-1,2:3,4-di-O-isopropylidene-α- d -galacto-heptodialdo-1,5-pyranose with 2-(trimethylsilyloxy)furan gave a mixture of stereoisomeric precursors. Condensation of 1,2:3,4-di-O-isopropylidene-α- d -galacto- hexodialdo-1,5-pyranose with the phosphate carbanion obtained from diethyl (2-furyl)methoxymethyl phosphonate led to 6-deoxy-7-C-(2-furyl)-1,2:3,4-di-O-isopropylidene- l -glycero-α- d -galactoheptopyranose (13). This was converted via the “Δ2”-butenolide route, to a mixture of stereoisomeric 5-C-(6-deoxy-α- d -galactopyranos-6-yl)-pentono-1,4-lactones of the d -allo- and d -talo configuration. In the third approach, 13 was transformed by the “enulose” approach to deamino-tri-(O-isopropylidene)tunicamine.

Alkylation of the anion 4 is only little stereoselective and leads to mixtures of stereoisomeric products 5A,B–9A,B. Proportion of stereoisomers depends strongly on the base employed. Condensation with acetaldehyde or benzaldehyde leads to four stereoisomeric products 11C–F and 12C–F, proportion of which depends also on the bases used. Decomplexation leads in the case of alkylated products to bromides 13, and in the case of aldol product 11 to bromohydrin 14 and epoxides 15 and 16.

A synthesis of tunicamine, the eleven-carbon atom sugar component of tunicamycin antibiotics, was described. The synthesis started from a derivative of 2-azido-2-deoxy-D-galactose ( 11 ) which was condensed with a furfuryl alcohol moiety. Achmatowicz-type transformation of this moiety to allo furanose system yielded a derivative of tunicamine. The synthesis required 11 steps and yielded 27 in 5.4% yield (from 11 ) and with good stereoselectivity.