Thieno indolizine

Thieno[2,3(3,2)-/]indolizines such as 50 undergo Diels-Alder reactions with diethyl azodicarboxylate (DEAD) to give the tetracyclic system 51 (Equation 6) <1995TL83>. 

Decroix and co-workers synthesized thieno[2,3(3,2)-/]indolizine 117 by polyphosphoric acid (PPA) catalyzed cyclization of 2-formyl+V-(thiophenyl)methylpyrazole 116 (Equation 26) <1995TL83>. 

Stelzner Fusion System. Stelzner fusion principles can be applied to heterocyclic components. However, strict application of the system is not always possible, and problems associated with deciding upon the degree of hydrogenation of the parent fused molecule often arise. For example, 34 and 35 are named thieno[3,2-a]indolizine and thieno-[2,3- >]indole by the IUPAC system. The Stelzner name for 35 would be thieno(2, 3 2,3)indole, but 34 cannot be similarly named, since in no... 

An ingenious method for the construction of the pyridine ring based on the tert-amino effect was used (1990RTC481) in the synthesis of a series of [3,2-Z>]-annu-lated thienoazines. Prolonged refluxing of diene aminodinitriles 166 in butanol affords thieno[3,2-Z>]indolizines and thieno[2,3-e]quinolizines of general formula 167. 

A similar mercaptoacetate addition reaction to 5-acyl-4,7-dioxo-4,7-dihydrobenzo[i]thiophene-2-carboxylates followed by cyclization and oxidation to give benzo[ 1,2-6 5,4-ft ]dithiophene-4,8-dione derivatives 29 has been shown <03H1689>. Nitrogen bridged heterocycles, 3-(benzylthio)thieno[3,4-6]indolizine derivatives 30 have been synthesized and intramolecular arene-arene interactions within these compounds were reported <03CPB75>. The arene-arene interaction leads to significant shifts in the proton NMR signals and red shifts in the absorption maxima. 

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