Isomaltose synthesis

In principle, several routes exist for enzymatic isomaltose synthesis. With respect to cost-effectiveness it is obvious that one should use substrates like sucrose or starch that can be exploited by dextransucrase (EC 2.4.1.5) or glucoamylase (EC 3.2.1.3), respectively. However, in both cases, isomaltose represents a side product which is released only in small proportions next to dextran or glucose as main products. Realization of higher yields requires extensive time and effort with respect to engineering of reaction and catalyst design. Based on kinetic investigations dextransucrase has been chosen for the production of isomaltose with sucrose as the substrate, and glucose as an acceptor (see Sect. 2.1). 

Isomaltose Synthesis Utilizing 2-Sulfonate Derivatives of D-Glucose, M. L. Wolfrom, K. Igarashi, and K. Koizumi,/. Org. Chem., 30, 3841-3844 (1965). 

Synthesis of Carba-maltose, Carba-isomaltose, Carba-cellobiose, and the Like 68... 

Such carba-disaccharides as validoxylamines A and B were synthesized as intermediary compounds in the total synthesis of validamycin antibiotics. Carba-disaccharides related to maltose, isomaltose, cellobiose, the trehaloses, and trehalosamine modifications have also been synthesized. 

Scheme 8.—Synthesis of Isomaltose (8) on a Light-sensitive, Solid Support ((P)).

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 ). 

Further findings relevant for the establishment of the chemical nature of enzymatic catalysis and technical apphcation followed within rather short time. Croft-Hill performed the first enzymatic synthesis, that of isomaltose, in 1898, allowing a yeast extract (df-glycosidase) to act on 40% glucose solution (Sumner and Somers, 1953). In 1900 Kastle and Loevenhart found that the hydrolysis of fat and other esters by lipases is a reversible reaction and that enzymatic synthesis can occur in a dilute mixture of alcohol and acid (Sumner and Myiback 1950). This principle was utilized for the synthesis of... 

Figure 2. Synthesis of maltose and isomaltose from ft-o-glucopyranose by glucoamylase, compared with the known hydrolytic reactions. The configurational inversion observed in the condensations indicates that the D-glucopyranosyl part of fi-D-glucopyranose is interchanged with hydrogen at the C, or C6 site of a second D-glucose molecule (78).

Ergezinger M, Bohnet M, Berensmeier S, Bucholz K (2006) Integrated enzymatic synthesis and adsorption of Isomaltose in a multiphase fluidized bed reactor. Eng Life Sci 5 1-8... 

Kishi and cowoikers " have also implemented alkenylchromium reagents for die synthesis of glycosides and C-methyl glycoside analogs. In the synthesis of the C-analog (217) of isomaltose (216), the C(5)—C(6) bond was established by die nickel(II) chromium(II)-mediated coupling of (Z)-iodoalkene... 

B. Lindberg, Action of strong acids on acetylated glycosides. V. Synthesis of (S-isomaltose octaacetate, Acta Chem. Scand., 3 (1949) 1355-1357. 

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