Hetaryl azides

Nitrosation of hetaryl acetic hydrazide 249 gives azide 250, which on thermolysis affords furazan 251 and 1,2,4-oxadiazole 252 (Scheme 165) (79JHC689). Depending on the solvent, different ratios of 251 and 252 were obtained. A higher proportion of furazan 251 (up to 70%) was formed in CHCI3. 

Amidines are also formed from less stable 1-hetaryl-220 and l-styryl-5-aminotriazolines.222,492,493 Thermolysis of the latter provides a method of synthesis of novel l-amino-2-azabutadienes (Scheme 176)492,493 Whereas cyanogen azide addition to dihydropyridines leads to bicycloazir-idines,241-243 addition of ethyl azidoformate yields the corresponding amidine 494 Likewise, indoles (103) react with picryl and sulfonyl azides to give... 

Later, Narasaka and coworkers reported that the scope of this transformation could be substantially improved with the use of Mn(III) catalysis [313]. These new reaction conditions allowed highly efficient employment of differently substituted simple non-activated alkyl-, aryl-, hetaryl- and even cydic vinyl azides 328 (Scheme 8.117). In addition, previously unreactive 1,3-diketones 33S could serve as feasible 1,3-dicarbonyl components in this formal [3 + 2] cycloaddition reaction, affording 2,3,5-tri-and 2,3,4,5-tetra-substituted pyrroles 336 in moderate to excellent yields... 

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