Teruo Yoshino

Synthetic studies with carbonates. Part 11. D-Glucopyranose 1-carbonate derivatives; pyrolytic behaviour and use for glucosylation of phenols

2,3,4,6-Tetra-O-acetyl-1-O-phenoxycarbonyl-β-D-glucopyranose (1), its 1-O-methoxycarbonyl analogue (3), and 2,3,4,6-tetra-O-benzoyl-1-O-phenoxycarbonyl-β-D-glucopyranose (5) underwent pyrolysis to give mixtures of various products whose composition depended on the structure of the starting material. However, the α-anomers of (1) and (3) were not susceptible to pyrolysis, even under more drastic conditions. Glucosylation reactions of phenols with the β-D-glucopyranose 1-carbonates were conducted autocatalytically to give the corresponding phenyl β-D-glucopyranoside derivatives in moderate yields. Especially useful was the synthesis of o-nitrophenyl and o-chlorophenyl glucopyranoside derivatives, which cannot be prepared through the Helferichs procedure, even under acid-catalysis conditions. A reaction mechanism involving an orthoester intermediate is suggested; such an intermediate was isolated and transformed into the corresponding glucopyranoside derivatives etc.

Synthetic studies with carbonates. Part 6. Syntheses of 2-hydroxyethyl derivatives by reactions of ethylene carbonate with carboxylic acids or heterocycles in the presence of tetraethylammonium halides or under autocatalytic conditions

Reactions of ethylene carbonate (1a) with a variety of carboxylic acids catalysed by tetraethylammonium halides gave the corresponding 2-hydroxyethyl esters along with the diesters arising from disproportionation of the former products induced by the quaternary ammonium halides. Formation of the disproportionation products could be minimized by use of a short reaction time. The autocatalytic reactions of (1a) with strongly acidic carboxylic acids at elevated temperature gave ethylene glycol diesters selectively. Reaction mechanisms are discussed. Reactions of cyclic carbonates such as (1a) and propylene carbonate(1b) with acid anhydrides or active acyl compounds such as p-nitrophenyl acetate in the presence of tetraethylammonium iodide gave alkylene glycol diesters or 2-acyloxyalkyl aryl ethers in high yields. An attempt to extend this reaction to cyclohexane-1,2-diyl carbonate was unsuccessful, but a reaction with 1,2-epoxycyclohexane succeeded; this enabled us to examine the stereochemistry of the reaction. Finally, N-2-hydroxyethylation of a series of heterocyclic compounds having acidic imino hydrogen atoms was performed, both with tetraethylammonium iodide as catalyst and without a catalyst.

Fusion reactions, involving activating agents, of some purine derivatives with 1,3,4,6-tetra-O-acetyl- 2-acylamido-2-deoxy-β-d-glucopyranoses

Abstract Fusion of 2-acetamido-1,3,4,6-tetra-O-acetyl-2-deoxy-β- d -glucopyranose, 1,3,4,6-tetra-O-acetyl-2-deoxy-2-phthalimido-β- d -glucopyranose, and 1,3,4,6-tetra-O-acetyl-2-benzamido-2-deoxy-β- d -glucopyranose with 2,6-dichloropurine, theophylline, and 6-benzylaminopurine in activating agents afforded the corresponding aminonucleosides in good yields. The simultaneous formation of a positional isomer was confirmed in three examples in the reactions with 2,6-dichloropurine and 6-benzylaminopurine. On the basis of these results, the potential effect of 2-acylamido functional groups on the reaction is discussed.

Reactions of d-mannitol carbonate derivatives catalyzed by tetraethylammonium bromide

Abstract Fusion of 1,2;3,4-di- O -isopropylidene- d -mannitol 5,6-carbonate ( 1 ) with nitrogen heterocycles in the presence of catalytic amounts of tetraethylammonium bromide ( 9 ) and with p -toluenesulfonamide present gave the corresponding 1-deoxy- d -mannitol-1-yl derivatives in good yields. Under the same reaction conditions, 1,2,3,4-tetra- O -acetyl- d -mannitol 5,6-carbonate ( 26 ) gave a good yield of 2,3,5,6-tetra- O -acetyl-1,4-anhydro- d -mannitol ( 27 ). Treatment of 1 with benzoyl chloride and 9 afforded 2- O -benzoyl-1-chloro-1-deoxy-3,4;5,6-di- O -isopropylidene- d -mannitol ( 36 ) and with acid anhydrides the 1,2-di- O -acyl derivatives of di- O -isopropylidene- d -mannitol. The use of 3,4- O -isopropylidene- d -mannitol 1,2;5,6-dicarbonate ( 37 ) with benzoyl chloride and acid anhydrides in the presence of 9 gave corresponding products through reaction of both carbonate groups. The reaction mechanisms are discussed.