Pterins, sugar

In 2002 Isay-type condensations for synthesis of 6-substituted pterins, including pterin sugar derivatives and 2-substituted quinoxalines, were developed under microwave irradiation conditions [103]. Interestingly, the isomer-free 6-substituted pterins desired were obtained in moderate to good yields whereas mixtures of both 6- and 7-isomers (major) are usually formed when conventional Isay type condensations are used. 

Goswami and Adak (2002) have developed a new method for the synthesis of 6-substituted pterins, pterin sugar derivatives and 2-substituted quinoxalines under microwave conditions. In addition to its simple reaction conditions, this procedure has the advantages of very short reaction times, simple experimental and work-up procedures and most importantly, its regiospecificity for the C-6 position of the pterin, which makes it useful for the synthesis of pterin and also quinoxaline heterocycles. 

There was no obvious explanation for the side-chain chirality of biopterin or its related aromatic pterin derivatives in the CD spectra. This fact requires that structural determination of all newly found pterins must be carried out by comparison with optically active authentic samples. Indeed, almost all compounds have been obtained as aromatic pterins through the exploration of naturally occurring rare pterins and their structures have been generally determined by chemical syntheses from sugar derivatives, as descried in Sect. 3.2. From the viewpoint of characteristic fluorescence emissions, the application of FDCD to the configurational analyses of aromatic pterin derivatives has been carried out in previous studies [64,65]. Since FDCD analysis of aromatic pterins is approximately 100 times more sensitive than normal... 

A regioselective synthesis of 6-substituted pterins 729, 730, and 731 was achieved using an MW-assisted direct Isay-type condensation of triamine 728 with methyl-glyoxal or aldohexoses to give under MWI, without addition of sodium bisulfate or hydrazine hydrate, 729 in 70% yield within 62 s and the sugar derivatives 730 and 731 in 40% and 38% yields, respectively, within 270 s (Scheme 141) (02TL8371). 

Hundreds of applications have been mentioned in the Zweig (1968) review acids, alkaloids, amino acids, antibiotics, antioxidants, food and feed additives, bases and amines, bile acids, carbonyls, dyes, enzymes, lipids, hydrocarbons, hormones, indoles, natural products, peptides, proteins, pesticides, plant growth regulators, pharmaceutical products, phenols, pigments (chlorophylls, xanthophylls, porphyrins, melanin, pterins, pteridines, anthocyanins, ilavonoids, etc.), polymers, purine and pyrimidine derivatives, quinones, RNA, DNA, organic sulfur compounds, steroids, sugars, toxins, vitamins, inorganic ions, and others. 

In a short note in 1939, Tschesche and Wolf described the properties of an acth e material that resembled the preparation of Karrer, et al. in that it shoued a negative or only slightly positive biuret test, but a positive ninhydrin both before and after hydrolysis (111). Their material, a white powder active in a dose of 40 mg., also had a negative Molisch and a negative Millon test it was free of flavine, purine, pterine, reducing sugar and phosphoric acid esters. 

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