Annulation Thorpe-Ziegler reaction

There are numerous applications of the Thorpe-Ziegler reaction for the synthesis of thiophenes and annulated thiophenes. Only selected examples can be covered here. For more examples see reviews (85MI1 86MI1 92MI1). 

The present review covers the Thorpe-Ziegler syntheses of 3-aminofurans, 3-aminopyrroles, 3-aminothiophenes, 3-aminoselenophenes, and diverse aminoazoles as well as the corresponding annulated systems that appeared from 1983 to 1996 but excludes examples considered in the 3-cyanopyridine review (92MI1). Moreover, examples are included that do not report a separate Thorpe-Ziegler cyclization but are likely to involve this type of reaction (e.g., cases in which precursors 1 were not isolated and identified but directly formed in the reaction mixture). Special attention is paid to synthetic aspects, although some reaction mechanisms are discussed too. 

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