Synthesis glucopyranose

A facile synthesis of carba- -D-glucopyranose (99) and its l antipode (104) was accomplished by means of resolution of the starting compound DL-( 1,3,5/2,4)-2,3-diacetoxy-4,5-dibromocyclohexane-1 -carboxylic... 

An alternative synthesis,by method h, was conducted by coupling 357 and 1,6-anhydro-4-0-(3,4-anhydro-6-deoxy-a-D-galactopyranosyl)-a-D-glucopyranose (392a) in 2-propanol at 120° this yielded a diastereoiso-meric mixture, from which, after the usual treatment, amylostatin (XG) was isolated in 20% yield. 

Figure 7.34 Synthesis of 2-acetamido-2-deoxy-/3-D-galactopyranosyluronic acid-(l —> 4)-2-acetamido-2-deoxy-D-glucopyranose...

The synthesis of a bridgehead sulfonium salt analogue 59, of the naturally occurring glycosidase inhibitor castanospermine, proceeded by a multistep procedure starting from 5-thio-d-glucopyranose pentaacetate <2000JA10769>. The desired bicyclic sulfonium salt 57 could not be obtained from the key bromide precursor... 

Fig. 20 Iterative synthesis of pseudoloigosaccharides using 6-desoxy-6-methoxyamino-a-D-glucopyranose.

In this article, the authors have endeavored to summarize the methods of synthesis and the proofs of constitution of all the known methyl ethers of D-glucopyranose and D-glucofuranose. Acyclic glucose ethers are not considered in this review. Later articles will deal with monosaccharides other than glucose. It has not been possible to discuss in full all the reactions involved, but to offset this disadvantage the bibliography has been made as complete as possible and tables have been compiled of the physical properties of the methyl-D-glucoses and of their more important derivatives. 

A one-pot, high-yielding synthesis of 1,2,3,4,6-penta-(9-acetyl-/ -D-( 1 -2H)glucopyranose (127) from tetra-O-acetyl-D-glucono-1,5-lactone (126) has been reported (172). Sodium borodeuteride reduction of 126, followed by in situ acetylation, gave the readily isolated and crystalline 127. The crystalline 2,4-dinitrophenyl 2,3,4,6-tetra-0-acetyl-/ -D-(l-2H)glucopyran-oside (128) was subsequently obtained from 127. 

Zychlinski prepared 1 -amino-5-deoxy-5-acetamido-2,3,4-tri-6)-acetyl- 3-D-glucopyranose 60 by a synthesis of 11 steps. This amine component undergoes the U-4CRs very well and the products are cleavable by water, but unfortunately they are not very stable. 

A much more systematic approach involves the use of p-chlorides carrying non-participating groups at C-2 as is exemplified by the Wolfrom synthesis of p-isomaltose octa-acetate from 1,2,3,4-tetra-O-acetyl-p-D-glucopyranose and 3,4,6-tri-0-acetyl-2-0-nitro-p-D-glucopyranosyl chloride In this work silver carbonate was used as acid acceptor and soluble silver perchlorate was fmmd to exert valuable catalytic influence, but later the perchlorate itself was used in an application to a tiisacchar-ide s mthesis which incorporated the trityl ether modification 2 ). 

HMF has been discovered for the first time in 1895 by Diill and Kiermeyer who independently introduced a method of synthesis of HMF that they named oxy-methylfurfurol [65, 66]. Later, Haworth and Jones studied the mechanism of this reaction and showed that the formation of HMF involved a triple dehydration of hexoses [67]. Other studies performed by Van Dam, Kuster and Antal showed that the dehydration of hexoses (especially fructose and glucose) involved two possible pathways (Scheme 5) [63, 68, 69]. The path 1 involves the dehydration of ring systems (fructopyranose or glucopyranose), while the path 2 is based on acyclic derivatives (glucose and fructose open chain). 

Several methods were described for the selective de-S-acetylation of 0-acetyl protected 1-thioglycoses. Sodium methoxide in methanol at low temperature (below -20 °C) was known to afford mainly the de-S-acetylated compound [16] or exclusively this compound when the reaction was quenched at low temperature by adding H-l- resin [17]. Demercuration of tetra-O-acetyl-l-phenylmercury(II)-thio- -D-glucopyranose (12) (Scheme 4) obtained by treatment of (8e) with phenylmercury(II)acetate afforded a convenient synthesis of tetra-0-acetyl-l-thio-/3-D-glucose (8a) [18]. This sequence applied to the a-anomer (10a) (Scheme 3) led to the expected de-S-acetylated compound (10b) [19]. Chemoselective deprotection of thioacetate at the anomeric position of peracetylated 1-thioglycoses was also achieved in good yield by action of cysteamine in acetonitrile or hydrazinium acetate in DMF [20,11]. 

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