Sucrose 3 ,6 -anhydro-, synthesis

Internal-displacement reactions to give sugar anhydrides are well known, and anhydro derivatives of sucrose have been prepared by treatment of the respective sulfonates or chlorides with a base. Buchanan and coworkers described the synthesis of 3, 6 -anhydrosucrose by treating 2,3,4,6,l, 3, 4 -hepta-0-acetyI-6 -0-(p-ni-trophenylsulfonyl)sucrose with sodium ethoxide in ethanol for 2 h under reflux.18 Similar treatment of 2,3,4,l, 3, 4, 6 -hepta-0-acetyl-6-chloro-6-deoxysucrose (46) with sodium methoxide in methanol, followed by acetylation, gave crystalline 2,4,l, 3, 4, 6 -hexa-0-acetyl-3,6-anhydrosucrose (47) in 83% yield.81 The H n.m.r. spectrum of 47... 

K. M. Taba, R. Koster, and W. V. Dahlhoff, Organoboron-disaccharides. 2. 2,6-Anhydro-/ -n-fructofuranosc by O-ethylboron-induced cleavage of sucrose, Synthesis, (1983) 1036-1037. 

Lemieux, R U, Huber, G, A chemical synthesis of sucrose. A conformational analysis of the reactions of 1,2-anhydro-a-D-glucopyranose triacetate, J. Am. Chem. Soc., 78, 4117-4119, 1956. 

The reaction of 1,2-anhydro sugars with alcohols promises to be a useful method for the preparation of glycosides. Brigl (S3) prepared methyl iS-D-glucopyranoside 3,4,6-triacetate by evaporating a solution of 1,2-anhydro-3,4,6-tri-0-acetyl-D-glucose in methanol to dryness. Recently, Lemieux and Huber (54) have extended the method to the synthesis of sucrose (see Chapter IX). 

It was not until a quarter of a century later that an authentic chemical synthesis was accomplished by Lemieux and Huber 3), They synthesized sucrose by reacting 3,4,6-tri-O-acetyl-l, 2-anhydro-a-D-glucopyranose with 1,3,4,6-tetra-O-acetyl-D-fructofuranose in a sealed tube at 100 for 104 hours. Chromatographic separation of the products of the synthesis gave a 5.5 % yield of sucrose octaacetate. Lemieux also synthesized octa-acetyl-jS-D-maltose 99) by treatment of the same anhydride with 1,2,3,6-tetra-O-acetyl-jS-D-glucose at 120° for 13 hours. 

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