Elner B. Rathbone

P.M.R. spectroscopy of monomethyl ethers of D-galactopyranose and its derivatives

Abstract P.m.r. parameters determined at 100 MHz for solutions in deuterium oxide) are presented for trimethyl ethers of D -galactopyranoside (eight), methyl D -galactopyranoside (eight), and galactitol (four). The anomeric and methoxyl proton chemical-shifts of these compounds are compared with those of the corresponding mono-, di-, and tetra-methyl ethers of D -galactopyranose and its derivatives. The results in this and earlier papers show that anomeric change greatly affects the 2-methoxyl signals (in derivatives of D -galactose, D -glucose, and D -mannose); change in configuration at C-4 ( D -galactose compared with D -glucose) affects the neighboring 3-methoxyl signal much more than the 4-methoxyl signal.

Partial benzoylation of sucrose

Abstract Tribenzoylation of sucrose followed by column chromatography gave a bitter fraction containing four tribenzoates, namely, 6,1′,3′-, 2,6,1′-, 2,6,6′-, and 6,3′,6′-tri- O -benzoylsucrose. A slower moving and less bitter fraction consisted of the expected major product, 6,1′,6′-tri- O -benzoylsucrose.

Characterisation of methyl derivatives of d-galactopyranose and methyl ethers of galactitol by p.m.r. spectroscopy

Abstract The 60- and 100-MHz p.m.r. spectra of methyl 2,3,4,6-tetra-O-methyl-α- d -galactopyranoside (1) and methyl 2,3,4,6-tetra-O-methyl-β- d -galactopyranoside (2) (dissolved in benzene, deuterium oxide, and other solvents) have been analysed for their methoxyl and anomeric proton signals, and compared with the spectra of the corresponding d -glucose derivatives, namely, methyl 2,3,4,6-tetra-O-methyl-α- d -glucopyranoside (3) and methyl 2,3,4,6-tetra-O-methyl-β- d -glucopyranoside (4). The spectrum of a mixture of 2,3,4,6-tetra-O-methyl-α- d -galactopyranose (5) and 2,3,4,6-tetra-O-methyl-β- d -galactopyranose (6) was obtained similarly, and the signals for all eight methoxyl groups were assigned for solutions in benzene and deuterium oxide. The spectra of 2,3,4,6-tetra-O-methyl- d -galactitol (7) and hexa-O-methylgalactitol (8) were analysed for their methoxyl-group signals in six solvents; these were assigned by using derivatives of 7 and 8 in which CH3O groups were replaced by CD3O groups to different extents. Compared with the use of the spectra of 1 and 2, the use of the p.m.r. spectrum of 7 (dissolved in benzene) was found to be a relatively simple method for identification of an unknown methyl ether of d -galactopyranose. The dependence of the spectra of the d -galactose derivatives (1, 2, 5, 6, 7 and 8) on concentration was measured for benzene solutions at 60 MHz; the spectra of these compounds in the other solvents used showed negligible dependence on concentration.

P.m.r. Spectroscopy of trimethyl ethers of D-galactopyranose its derivatives

Abstract P.m.r. parameters determined at 100 MHz for solutions in deuterium oxide) are presented for trimethyl ethers of D -galactopyranoside (eight), methyl D -galactopyranoside (eight), and galactitol (four). The anomeric and methoxyl proton chemical-shifts of these compounds are compared with those of the corresponding mono-, di-, and tetra-methyl ethers of D -galactopyranose and its derivatives. The results in this and earlier papers show that anomeric change greatly affects the 2-methoxyl signals (in derivatives of D -galactose, D -glucose, and D -mannose); change in configuration at C-4 ( D -galactose compared with D -glucose) affects the neighboring 3-methoxyl signal much more than the 4-methoxyl signal.

Conformational analysis of 1,2:3,4-di-O-isopropylidene-α-d-galacto-octopyranose derivatives: a 1H- and 13C-N.M.R.-spectral and x-ray comparative study

Abstract The pyranoid conformations of 7-acetamido-6,7,8-trideoxy-1,2:3,4-di- O -isopropylidene- d - glycero -α- d - galacto -octopyranose ( 3 ) and 7-acetamido-7,8-dideoxy-1,2:3,4-di- O -isopropylidene- l - threo -α- d - galacto -octopyranose ( 4 ) in solution have been determined by calculation of the dihedral angles from the vicinal, proton-proton coupling-constants, using three modifications of the Karplus equation. Of these, only the equation 3 J (HCCH)(φ)  (7.48  0.74 -ΣδE x )  (2.03  0.17 ΣE x )cos φ + (4.60  0.23 ΣδE x )cos 2φ + 0.06 (Σ ± ΔE x )sin φ + 0.62 (Σ ± ΔE x )sin 2φ indicates that the pyranoid part of 3 and 4 has the ° S 2 conformation, very slightly distorted towards ° H 5 , in agreement with the conformations determined for the crystalline state. Analysis of the 1 H-n.m.r. data for a series of 1,2:3,4-di- O -isopropyl-idene-α- d - galacto -octopyranose derivatives shows that the pyranoid parts of these compounds adopt the same conformation as that found for 3 and 4 .

P.M.R. spectroscopy of O-methyl derivatives of d-galactopyranose and related compounds in solution in deuterium oxide

Abstract The results obtained from a study of the p.m.r. spectroscopy of deuterium oxide solutions of d -galactopyranose and its partially and fully methylated derivatives are discussed. The methoxyl-proton chemical-shifts for some of these compounds are compared with those of corresponding derivatives of d -glucose, d -mannose, and the hydrochlorides of 2-deoxy-2-(methylamino)- d -glucose and - d -galactose. The effects, on the methoxyl and anomeric proton chemical-shifts, of anomeric change, methylation of neighboring hydroxyl groups, and change in configuration of adjacent carbon atoms bearing a hydroxyl or methoxyl group are noted.

C-methylation of sucrose: synthesis of 6- and 6′-C-methylsucrose

Abstract 2,3,4,6,1′,3′,4′-Hepta- O -benzylsucrose, obtained by acid-catalysed hydrolysis of the 6′- O -trityl derivative, was oxidised with the Pfitzner-Moffatt reagent and the product was alkylated with methylmagnesium iodide. Removal of the protecting groups then gave a mixture of diastereomers, namely 7-deoxy-β- d - altro and -α- l - galacto -hept-2-ulofuranosyl α- d -glucopyranoside. Application of this reaction sequence to 2,3,4,1′,3′,4′,6′-hepta- O -benzylsucrose afforded β- d -fructo-furanosyl 7-deoxy- dl - glycero -α- d - gluco -heptopyranoside.