Fused polyaza systems

Molecular orbital calculations have been used to analyze the stabilities of dihydropterins 06H1705 . The photochemistry of 6-(hydromethyl)pterin in aqueous solution has been investigated 06HCA1090 . 

A new synthesis of pterins based on the acylation of 4-amino-5-nitrosopyrimidines with dienoic acid chlorides, followed by a high-yielding intramolecular hetero DA cycloaddition and cleavage of the N—O bond has been reported 06HCA1140 . Several new substituted pterins have been obtained in an efficient one-pot procedure using N,N dimethyldichloromethyleniminium chloride (phosgeniminium chloride) and a suitable pyrazine 06H933 . 

Pteridines have been prepared in good yields from 6-amino-5-nitrosouracils with Meldrum s acid in the presence of piperidine as catalyst under thermolytic conditions 06SC3085 . Novel 6-formylpterin derivatives have been synthesized and their neuroprotective effects studied 06OBC1811 . 

The synthesis of 4-trifhioromethylpyrimido[4,5-c]pyridazin-5,7-diones from 6-hydrazinouracils and l,l,l-trifluoropropane-2,3-dione monohydrates has been reported 06H1875 . Novel pyrimido[4,5-c]pyridazines have been synthesized and investigated as inhibitors of lymphocyte specific kinase 06BMCL4257 06H2037 . 

Reaction of 3-alkylamino-6,8-dimethylpyrimido[4,5-c]pyridazin-5,7-diones 80 with cyclohexyl and cycloheptylamines afforded novel cycloalkano bis(pyrrolo[2,3-c]pyrimido[5,4-e]pyridazines 81 06T652 . 

Two reports deal with the synthesis and antitumor activity of 3,6-disubstituted 1,4-dihydro-1,2,4,5-tetrazine derivatives 05JCR(S)91 05BMCL3174 . In the latter, 

The number of publications in this category is considerable, even though purine and pyrimidine nucleosides have not been included. 

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Triazines, tetrazines, and fused polyaza systems 89PHC263 90PHC203 91PHC223 92PHC204 93PHC239. 

Triazines, tetrazynes, and fused polyaza-systems 00PFIC294, 01PHC296, 02PHC310. 

Triazines, Tetrazines and Fused Ring Polyaza Systems... 

Triazines, tetrazines and fused ring polyaza systems... 

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