Maltose -, synthesis

Fig. 8. Stereochemistry of reactions catalyzed by maltose phosphorylase with inversion of configuration. (A) a-Maltose synthesis from /3-D-glucopyranosyl phosphate and the reverse phosphorolysis of a-maltose (B) a-maltose synthesis from /3-D-glucopyranosyl fluoride plus a-D-glucose. X represents a protein component whose interaction with the axial 1-OH of a-D-glucopyranose is required to activate all reactions promoted by the enzyme. Reproduced from Tsumuraya et al., Arch. Biochem. Biophys., 281 (1990) 58-65, with permission of Academic Press.

Maltose, l- 4- -link in, 998 molecular model of, 998 mutarotation of, 998 structure of, 998 Manicone, synthesis of. 805 Mannich reaction. 915 Mannose, biosynthesis of, 1011 chair conformation of, 126 configuration of, 982 molecular model of, 126 Margarine, manufacture of, 1063 Markovnikov. Vladimir Vassilyevich. 192... 

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. 

A similar synthesis starting from the derivatives of maltose (55), lactose (46), and cellobiose (57) to give the L-asparagine derivatives 56,48, and 58, respectively, was accomplished by Dunstan and Hough.46... 

The living character of the ROMP promoted by the initiator Ru(CHPh)(Cl)2 (PCy3)2 (Cy = cyclohexane) was tested with the synthesis of diblock, triblock, and tetrablock copolymers of norbornene derivatives carrying acetyl-protected glucose, [2,3,4,6-tetra-O-acetyl-glucos-l-O-yl 5-norbornene-2-carboxylate], A or maltose groups, [2,3,6,2/,3/,4/,6/-hepta-0-acetyl-maltos-1-O-yl 5-norbornene-2-carboxylate], B, shown in Scheme 41 [102]. The AB, ABA, and ABAB structures were prepared by sequential addition of monomers with narrow molecular weight distributions to quantitative conversions. 

F. Paul, E. Oriol, D. Auriol, and P. Monsan, Acceptor reaction of a highly purified dextransucrase with maltose and oligosaccharides. Application to the synthesis of controlled molecular weight dextrans, Carbohydr. Res., 149 (1986) 433-441. 

The third group is that of compounds which may potentially be transported by the PTS and inhibit cAMP production. Cellulase synthesis is initiated after these compounds are consumed for cell growth. This group includes D-glucose, D-fructose, maltose, mannitol, glycerol, sorbitol, and -methyl glucoside. The presence of these compounds in Solka Floe fermentations, enhanced enzyme yields (132 to 254%) but the time required to complete cellulase synthesis took longer (106 to 148%) than the control. 

We first describe a synthesis of alpha cyclodextrin. The synthetic plan is shown in Scheme 1. An immediate precxirsor for 1 could be the perbenzylated precursor 5, which could be cleaved to give a linear glucohexaosyl fluoride 6. This key intermediate 6 is obtainable from the maltose derivatives 8 and 9 through the intermediacy of the glucohexaose derivative 7 ... 

Scheme 6.176 Synthesis of bifunctional saccharide-based amine thioureas 207-210 from the corresponding glucose-, maltose, and lactose-isothiocyanates, respectively.

In the thiomaltose series the same approach was used for the synthesis of 4,4 -dithiomaltotriosides (48a,48b) (Scheme 16) [43]. However the sequence of reactions is much longer since the chloride intermediate (46) was formed in 83% yield only when the peracetylated 4-thiomaltose (45) was used, and the 1,4-dithiomaltose peracetate (47b) was obtained via the corresponding S-benz-oyl analogue (47 a). Under these conditions the 4,4 -dithiomaltotriosides were obtained in 20% overall yield from the 4-thio-)3-maltose peracetates (45). 

The same methodology extended to maltose afforded the bifunctional syn-thons (55b, 55d) which led to the hemithiomaltooctaoses (56d-g) in good yield. However the reaction of (56 g) led to the synthesis of the hemithiocyclo-maltooctaose (57a) in a disappointing yield of 3% (Scheme 19) [46]. 

The first synthesis of octa-0-acetyl-/3-maltose was reported by Le-mieux10 in 1953. When 1,2,3,6-tetra-0-acetyl-/3-D-glucopyranose was heated with 3,4,6-tri-0-acetyl-l,2-anhydro-a-D-glucopyranose for 13 h at 100°, it gave a mixture from which the product was isolated, after acetylation, in 8.7% yield. Octa-0-acetyl-/3-maltose has been obtained in 43.6% yield by way of condensation of 3,4,6-tri-0-acetyl-2-0-ben-zyl-/3-D-glucopyranosyl chloride with l,2,3,6-tetra-0-acetyl-/3-D-gluco-pyranose.11... 

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