Of cyclic sugars

Replacement by Iodine, of Non-contiguous Primary and Secondary Sulfonyloxy Groups in Derivatives of Cyclic Sugars... 

Soon after the appearance of Oldham and Rutherford s classic paper,20 Levene and his school began a systematic study of the behavior of cyclic-sugar derivatives bearing only secondary O-sulfonyl groups. In 1933, they found that 5,6-0-benzylidene-l,2-0-isopropylidene-3-0-tosyl-D-glucose is completely unaffected361 under Oldham and Rutherford s conditions, but that the sulfonyloxy groups of 5-O-acetyl- and 5-0-benzoyl-l,2-0-... 

Ohtake, H, Ichiba, N, Ikegami, S, A highly stereoselectiye construction of (3-glycosyl linkages by reductiye cleayage of cyclic sugar ortho esters, J. Org. Chem., 65, 8171-8179, 2000. 

HAWGRTH STRUCTURES Fischer representations of cyclic sugar molecules use a long bond to indicate ring structure. A more accurate picture of carbohydrate structure was developed by the English chemist W. N. Haworth (Figure 7.7). 

The study of the conformations of cyclic sugars was developed more fully by Reeves in a series of papers, beginning in 1949, dealing with the formation of complexes of sugars and their derivatives in cuprammonia solution. Reeves was able to provide experimental evidence to indicate that some pyranoid sugars indeed adopt chair conformations in solution, and that, in such cases, one chair form usually appeared to preponderate over the other. Boat or skew conformations were considered possible if the nonbonded interactions between the substituents in the chair conformation became too large. " Reeves s investigations have formed the basis of much subsequent work in the conformational analysis of cyclic carbohydrate... 

Our aim in this chapter is to present the most important advances in the domino reactions of carbohydrates based on the metal-promoted ring opening of cyclic sugars. These procedures, promoted by different low-valent organometaUic reagents, start with the addition of the metal to an electrophihc site (i.e., an alkyl hahde, a carbonyl, an alkene, or an alkyne), followed by reductive ehmination to the open-chain sugar. From this open-chain sugar intermediate, the next reaction takes place under the same reaction conditions. 

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