Enzymic methods synthesis

Synthesis of sucrose 6 -phosphate by an enzymic method using uridine 5 -(a-D-glucopyranosyl diphosphate) plus D-glucose 6-phosphate has been reported.126-131 The first, unambiguous, chemical synthesis of sucrose 6 -phosphate was achieved by Buchanan and coworkers.18 The reaction of 2,3,4,6,l, 3, 4 -hepta-0-acetylsucrose, prepared by five steps of synthesis, with cyanoethyl phosphate in pyridine gave a crude product from which sucrose 6 -phosphate was isolated as the barium salt. 

The use of a range of oxidative enzymes in synthesis is covered in Chapter 11, whilst the very powerful technique of regio- and stereo-specific biohydroxylation of even complex molecules by femienting whole-cell methods is covered in Chapter 12. 

Enantiopure epoxides and vicinal diols are important versatile chiral building blocks for pharmaceuticals (Hanson, 1991). Their preparation has much in common and they may also be converted into one another. These chirons may be obtained both by asymmetric synthesis and resolution of racemic mixtures. When planning a synthetic strategy both enzymic and non-enzymic methods have to be taken into account. In recent years there has been considerable advance in non-enzymic methods as mentioned in part 2.1.1. Formation of epoxides and vicinal diols from aromatics is important for the break down of benzene compounds in nature (See part 2.6.5). 

Previous accounts of enzymic methods in organic synthesis include four reviews3-6 and a chapter in a book,7 while immobilization of enzymes is discussed at length in three volumes8 10 of Methods in Enzymology. The older literature may be found in an earlier volume of the same collection.11... 

Starting from achiral materials, two stereoisomeric phosphonylated dihydroxy pyrrolidines (275) and (276), containing four stereogenic centers, have been synthesized enantioselectively, employing a combination of enzymatic and transition-metal-mediated methods. Both compounds contain features of the transition state of the enzyme-catalysed fucosyl transfer reaction and represent building blocks of potential inhibitors against this class of enzymes. The synthesis of new sugar-derived phosphonic acids e.g. (277) from protected... 

The enzymic synthesis of sucrose resulted in some publicity that came to the attention of officials of the Coca Cola Company, who were having difficulty in obtaining sucrose because of wartime rationing. The company sent a representative to Berkeley to ascertain whether commercial quantities of sucrose could be made by the enzymic method. Hassid and his associates were away on vacation at the time, so the Coca Cola emissary discussed the problem with Prof. 

We have already approached the synthetic problems relative to these oligosaccharides. Concerning glycosylamines, we have given the preparation of glucosides of asparagine in Section 3.6.2 and, as a synthetic example using enzymic methods, the synthesis of a peripheral sequence, 12.21. 

Simple procedures for the preparation of NMN+ by chemical or enzymic methods have been reported and although the phosphorylating agent metaphosphoric acid used in the chemical phosphorylation of nicotinamide 2, 3 -0-isopropylidene ribofuranoside is relatively imsophisticated, the synthesis can be carried out on a large scale with moderate yields. The stereo-... 

Since these early studies, numerous additional procedures have been developed for the synthesis of chiral labeled acetic acid and other chiral labeled molecules by chemical (I41-15I) and enzymic methods 152-155). The malate synthase/fumarase system described above continues to be the most widely used method for the stereochemical analysis of chiral labeled acetic acid resulting from the degradation of product molecules containing chiral methyl groups. 

Sarmentose. 2,6-Dideoxy,3,0,methyt-xylo-hexose. C,Hm04 mol wt 162.18. C 51.84%, H 8.70%. O 39.46%. A methyl ether of a 2-desoxyhexomethylose, isomeric with cymarose. Obtained on hydrolysis of sarmentocymarin, a glycoside isolated from seeds of Strophanthus sarmentosus DC., Apacynaceae by the enzymic method Jacobs, Heidelberger, J. Biot Chem. 81, 765 (1929) Jacobs, Bigelow, ibid. 96, 355 (1932). Synthesis H. Hauenstein, T. Reichstein, Heh. Chim. Acta 33. 446 (1950). 

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