Triazoles and 1,2,3-Triazolines Utilized in Organic Synthesis

4-Aminotriazoles which are appropriately substituted at the C(5)-position are important intermediates for the synthesis of 8-azapurines. These reactions have been reviewed 86AHC(39)ll7 . The pharmaceutically useful acyclonucleosides bearing 1,2,3-triazolines and 8-azapurines have been synthesized 888879). 4,5-Diaminotriazoles react with 1,2-dicarbonyl reagents to give 1,2,3-triazolo[4,5- )]pyrazines. 4,5-Diamino-2-phenyltriazole and sulfur monochloride afford the triazolo[4,5-c][l,2,5]thiadiazole (855) 86AHC(40)129 . The synthesis of triazolopyridines from triazoles has been described in a review 83AHC(34)79 . For further applications of substituted triazoles in preparations of complex heterocycles, see Section 4.01.4. 

The synthetic applications of substituted 1,2,3-triazole 1-oxides and 1,2,3-triazolium-l-imides in the preparations of 1,2,3-triazines, 1,3,4,5-oxo- and -thia-triazines, and 1,2,3,5-tetrazines have been discussed in Section 4.01.4.12. Conversions of 1,2,3-triazolines into aziridines either thermally or photochemically were described in detail in CHEC-I 84CHEC-1(5)691 and in a review 84AHC(37)217 . Some recent developments are discussed in Section 4.01.5. 

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