Michael Ralph Jenner

Reaction of methanesulphonyl chloride-N,N-dimethylformamide with partially esterified derivatives of sucrose

Abstract Treatment of sucrose 2,3,3′,4′,6-penta-acetate (1) with methanesulphonyl chloride- N,N -dimethylformamide (reagent A ) gave the 1′,4,6′-trichloride 2 , the 1′- O -formyl-4,6′-dichloride 3 , the 4,6′-dichloride 4 , and the 1′,4-di- O -formyl-6′-chloride 5 . De-esterification of 3 afforded the unsubstituted 4,6′-dichloride 6 which, on acetylation, gave the corresponding hexa-acetate 7 , also prepared by acetylation of 4 . In compounds 2, 3, and 4, substitution at C-4 by chloride ion occurred with inversion of configuration. The structure of 5 was confirmed by conversion into the known 6′chloro-6′-deoxysucrose hepta-acetate by de-esterification followed by acetylation. Treatment of sucrose 1′,2,3,3′,4′,6′-hexa-acetate (10) with the reagent gave the 4,6-dichloride 11 and 4- O -formyl-6-chloride 12 . The formyl group in 12 was selectively removed by using an anion-exchange resin to give 16 . De-esterification of 12 with methanolic sodium methoxide gave 6-chloro-6-deoxysucrose (13) which, on acetylation and benzoylation, afforded the hepta-acetate 14 and the hepta-benzoate 15, respectively. Alternatively, 15 was prepared by the reaction of 1′,2,3,3′,4,4′,6′-hepta- O -benzoylsucrose with reagent A . Treatment of 14 with sodium methoxide in methanol followed by acetylation gave 3,6-anhydrosucrose hexa-acetate (24) . Reaction of sucrose 2,3,3′,4,4′-pentabenzoate (17) with reagent A gave the known 1′,6,6′-trichloro-1′,6,6′-trideoxysucrose pentabenzoate (18) and 1′- O -formyl-6,6′-dichloride 19 . Treatment of 19 with anion-exchange resins selectively removed the formyl group to give 20 . The structure of 20 was confirmed by conversion into the 1′-chlorosulphate-6,6′-dichloride (21) . Treatment of sucrose 1′,2,3,3′,4,4′-hexabenzoate (22) with reagent A gave the expected 6,6′-dichloride (23) .

The first replacement of a chlorosulphonyloxy group by chlorine at C-2 in methyl α-D-glucopyranoside and sucrose derivatives☆

Abstract Treatment of methyl 3- O -acetyl-4,6- O -benzylidene-α- D -glucopyranoside 2-chlorosulphate ( 2 ), 3,4,6,3′,4′,6′-hexa- O -acetylsucrose 2,1′-bis(chlorosulphate), 3,4,6,3′,4′,6′-hexa- O -acetyl-1′- O -benzoylsucrose 2-chlorosulphate, and 3,4,3′,4′-tetra- O -acetyl-6,6′-dichloro-6,6′-dideoxysucrose 2,1′-bis(chlorosulphate) with lithium chloride in hexamethylphosphoric triamide gave the corresponding chlorodeoxy- manno derivatives. Treatment of the 2-chlorosulphate 2 with such nucleophilic reagents as lithium bromide, sodium azide, sodium chloride, and sodium benzoate in hexamethylphosphoric triamide gave the 2-hydroxy compound as a major product. Selective chlorination at C-1′ was achieved when 3,4,6,3′,4′,6′-hexa- O -acetylsucrose was treated with sulphuryl chloride in a mixture of pyridine and chloroform.

Ring-opening reactions of sucrose epoxides: Synthesis of 4′-derivatives of sucrose☆

Abstract The 2,1′- O -isopropylidene derivative ( 1 ) of 3- O -acetyl-4,6- O -isopropylidene-α- d -glucopyranosyl 6- O -acetyl-3,4-anhydro-β- d - lyxo -hexulofuranoside and 2,3,4-tri- O -acetyl-6- O -trityl-α- d -glucopyranosyl 3,4-anhydro-1,6-di- O -trityl-β- d - lyxo -hexulofuranoside have been synthesised and 1 has been converted into 2,3,4,6-tetra- O -acetyl-α- d -glucopyranosyl 1,6-di- O -acetyl-3,4-anhydro-β- d - lyxo -hexulofuranoside ( 2 ). The S N 2 reactions of 2 with azide and chloride nucleophiles gave the corresponding 2,3,4,6-tetra- O -acetyl-α- d -glucopyranosyl 1,3,6-tri- O -acetyl-4-azido-4-deoxy-β- d -fructofuranoside ( 6 ) and 2,3,4,6-tetra- O -acetyl-α- d -glucopyranosyl 1,3,6-tri- O -acetyl-4-chloro-4-deoxy-β- d -fructofuranoside ( 8 ), respectively. The azide 6 was catalytically hydrogenated and the resulting amine was isolated as 2,3,4,6-tetra- O -acetyl-α- d -glucopyranosyl 4-acetamido-1,3,6-tri- O -acetyl-4-deoxy-β- d -fructofuranoside. Treatment of 5 with hydrogen bromide in glacial acetic acid followed by conventional acetylation gave 2,3,4,6-tetra- O -acetyl-α- d -glucopyranosyl 1,3,6-tri- O -acetyl-4-bromo-4-deoxy-β- d -fructofuranoside. Similar S N 2 reactions with 2,3,4,6-tetra- O -acetyl-α- d -glucopyranosyl 1,6-di- O -acetyl-3,4-anhydro-β- d - ribo -hexulofuranoside ( 12 ) resulted in a number of 4′-derivatives of α- d -glucopyranosyl β- d -sorbofuranoside. The regiospecific nucleophilic substitution at position 4′ in 2 and 12 has been explained on the basis of steric and polar factors.

Synthesis and reactions of cyclic acetal derivatives of 6,6′-dichloro-6,6′-dideoxysucrose☆

Abstract Treatment of 6,6′-dichloro-6,6′-dideoxysucrose with a combination of 2,2-dimethoxypropane, N,N -dimethylformamide, and toluene- p -sulphonic acid (reagent A), followed by acetylation, gave the 1′,2:3,4-diacetal 1 (39%) and the 1′,2-acetal 2 (37%). A similar reaction of methyl 6-chloro-6-deoxy-α- D -glucopyranoside with reagent A yielded the corresponding 2,3- and 3,4-acetal derivatives in yields of 29% and 9%, respectively. The structures of 1 and 2 have been confirmed by 1 H-n.m.r. spectroscopy and by chemical transformations.

Use of dimethoxydiphenylsilane, NN-dimethylformamide, and toluene-p-sulphonic acid as a novel acetalating reagent

Reaction of sucrose with a combination of dimethoxydiphenylsilane, NN-dimethylformamide, and toluene-p-sulphonic acid gave a mixture of 1′,2-O-(diphenylsilylene)sucrose and 1′,2 : 6,6′-di-O(diphenylsilylene) sucrose, from which the 1′,2-silylene acetal has been isolated directly as its hexa-acetate (1) in 18% yield; the 1′,2 : 6,6′-disilylene acetal tetra-acetate (2) has been isolated after column chromatography.