Pteridines 6,7,8,9-tetrahydro

Oxidations in the pteridine series comprise (i) replacement of hydrogen by hydroxyl, (ii) glycol formation at the central C=C bond (iii) the removal of hydrogen atoms from dihydro and tetrahydro derivatives. 

Pteridine, l,3-dimethyl-2-imino-4-oxo-7-phenyl-3,4-tetrahydro-synthesis, 3, 305... 

Pteridine, 6-oxo-5,6,7,8-tetrahydro-electrochemistry, 3, 285 Pteridine, 7-oxo-5,6,7,8-tetrahydro-electrochemistry, 3, 285 Pteridine, 2-phenyl-structure, 3, 266 Pteridine, 4-phenyl-structure, 3, 266 Pteridine, 7-phenyl-oxidation, 3, 305 Pteridine, 2,4,6,7-tetraamino-synthesis, 3, 291 Pteridine, 2,4,6,7-tetrabromo-reactions, 3, 291 Pteridine, 2,4,6,7-tetrachloro-hydrolysis, 3, 291 properties, 3, 267 Pteridine, 1,2,3,4-tetrahydro-structure, 3, 280 Pteridine, 5,6,7,8-tetrahydro-reduction, 3, 280 synthesis, 3, 305 Pteridine, 2,4,6,7-tetramethyl-NMR, 3, 266... 

The importance of the dihydro and tetrahydro oxidation states of pterins in biology has stimulated interest in the study of the chemical properties of these compounds, especially with respect to electron-transfer and radical reactions. It has become apparent, perhaps unsurprisingly, that the stability and reactivity of these oxidation states are very sensitive to substituent effects and the much greater stability of the fully conjugated pteridines is most evident. The oxidation of tetrahydropterins and the reduction of dihydropterins have become especially important in the chemistry of nitric oxide production in nature and in oxidative stress but the accumulation of relevant facts has not led so far to a detailed understanding of the chemical property relationships. Relevant information is summarized in the following section. 

The one-step synthesis of further tri- and tetracyclic pteridine derivatives from 2-aminopyrazine 153 has also been described <2001JHC1173>. Cyclic analogues of A -[bis(methylthio)methylene]amino reagents such as 2-(methylthio)-2-thiazoline, 5,6-dihydro-2-(methylthio)-4//-l,3-thiazine, 2-(methylthio)-2-imidazoline, 2-(methylthio)-l,4,5,6-tetrahydro-pyrimidine, 2-(methylthio)-2-pyrazine, and 2-chloropyrimidine reacted with aminopyrazine 153 to afford thiazolo/thia-zino[2,3-3]- 159 ( = 1 (53%), n = 2 (42%)), imidazo/pyrimidino[2,l-/ ]- 160 ( = 1 (53%), = 2 (57%)), pyrazino[2,l-/ ]-161 (21%), and pyrimido[2,l-/ ]-pteridine 162 (42%) derivatives, respectively. 

The identity of a glucosylated derivative of L-biopterin from Synechococcus sp. PGG 7942 has been confirmed as the 2 -0-a-glucosyl derivative by 2-D NMR spectroscopy <2001PTR121>. Tetrahydro-D-monapterin 223 has been identified as the native pteridine in Tetrahymena pyriformis <2001HGA918> the configuration and stmcture were confirmed by comparison with synthetic samples of known configuration. 

DMA followed by sodium methoxide furnished ylide (479) which was immediately condensed with diethyl JV-(p-formylbenzoyl)-L-glutamate to afford (480). Catalytic hydrogenation gave the 5,6,7,8-tetrahydro derivative oxidation with hydrogen peroxide followed by hydrolysis of the ester groups then gave (478). This is the first report of the preparation and use of a pteridine ylide in the Wittig reaction. 

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