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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.

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.

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.

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.

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.

The 1H and 13C NMR spectra of trans- and cis-tert-butyl 2-methoxy-5,6-dihydro-2H-pyran-6-carboxylates (1 and 2) and 6,6′-disubstituted 2-methoxy-5,6-dihydro-2H-pyrans (3-7) have been recorded. HH and CH coupling constants are discussed in terms of the 1H6⇄6H1 conformational equilibrium. It has been found that 1 occurs exclusively in the 1H6 conformation, whereas its cis isomer, 2, exists in an equilibrium of both half-chair forms. 6,6′-Disubstituted 2-methoxy-5,6-dihydro-2H-pyrans 3-6 display spectral and conformational behaviour similar to that of 1, whereas 7 resembles 2 in this respect.

The sum of coupling constants of proton H-6 for conformations H1 and 1H of the 6-substituted 5,6-dihydro-α-pyran derivatives have been determined with the aid of appropriate, conformationally biased compounds. With the use of these values and the PMR spectra of the title compounds, thermodynamic values of their conformational equilibria and the conformational preferences of the carbomethoxy, hydroxymethyl and acetoxymethyl groups, have been evaluated.