Carbohydrates substituent groups

Note 2. The use of prefixes ending in -ylidene for gem-bivalent substituent groups is traditional in the carbohydrate field, although no longer recommended in general organic nomenclature [14],... 

Carbohydrate chemistry contains many examples of intramolecular migration of substituent groups. The largest number of these involve acyl groups, but migrations in phosphoric esters, and certain ethers have also been reported. Surprisingly, the topic has not been the subject of a comprehensive review, but there are several useful summaries thereof.539-542 In this Section, mainly those examples that have... 

Abstract This review provides an overview of some of the more recent work directed to exploit radical-based chemistry for the modification of some of Natures most important biomolecules, such as amino acids, peptides, and carbohydrates. Radical reactions are particularly advantageous for carrying out a variety of structural modifications on biomolecules as the reaction conditions are typically compatible with a wide variety of functional groups and solvents. An array of effective synthetic transformations will he discussed including selective side chain and backbone modifications of amino acids and peptides, along with methods for the transformation of carbohydrate substituents, as well as fragmentation and cyclizations reactions for the preparation of either structurally modified carbohydrates or chiral building blocks. 

The review by Neely tabulated the characteristic frequencies of several common, substituent groups that are of interest in carbohydrate chemistry, and discussed in detail the results of the structural analysis - of pyranose derivatives in the region 730-960 cm.-. In addition, brief outlines were also given of a similar analysis (see Ref. 69) of furanose derivatives (less fruitful than that of pyranose derivatives) and of the investigations of variation in hydrogen bonding in celluloses. 

The characteristic frequencies of some common substituent groups, such as C=0, NH, S=0, and benzene ring, were tabulated in the earlier review. Carbohydrate nitrates and sulfonates have since been studied in detail and another useful correlation that enables the methoxyl group to be detected by means of a characteristic C—H stretching band at 2882... 

The last phases of B. R. Baker s work that was completely devoted to carbohydrate chemistry were carried out between 1963 and 1966, when he was in residence at the State University of New York at Buffalo. He studied Sn2 displacements in comparison with neighboring-group displacements in the l,2 5,6-di-0-isopropylidene-n-mannitol and related systems, and showed that the competition between the two types of replacement reaction depends on the nucleophilic nature of the substituent group and the nature of the neighboring group and he used... 

R. D. Guthrie and J. Honeyman, Periodate oxidation. I. Structure and some reactions of periodate-oxidised methyl 4,6-O-benzylidene-a-D-glucoside, J. Chem. Soc., (1959) 2441-2448. A. S. Perlin, Hydroxyl proton magnetic resonance spectra in relation to ring size, substituent groups, and mutarotation of carbohydrates. Can J. Chem, 44 (1966) 539-550. 

The second pathway to prepare pyridylglycoporphyrins considers the derivatization of pyridylporphyrins with carbohydrate derivatives (Scheme 36). Porphyrins shoidd then have the required substituent groups for coupling with the sugar moieties. In this way the neutral and cationic acid series 198 and 199 were prepared from precursor 196, previously activated to ester 197 and then reacted with the protected galactose derivative [ 134,149]. 

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