The reaction between benzynes and imidazo[1,2-a]pyridines (pyrimidines) to form benzo[a]imidazo[5,1,2-cd]indolizines and 2,3,9c-triazocyclopenta[j,k]fluorenes has been studied computationally and experimentally. It is found that these reactions take place via tandem [(pi)8(s) + (pi)2(s)] and [(sigma)2(s) + (pi)6(s) + (sigma)2(s)] processes. The [8 + 2] cycloaddition steps are essentially barrierless, and the aromatization steps occur via highly synchronous aromatic transition structures. From an experimental standpoint, the reaction is feasible under microwave irradiation and using 2-(trimethylsilyl)phenyl triflates as benzyne precursors. Depending on the substitution pattern in the starting triflate a complete regiocontrol of the reaction can be achieved. The tetracyclic compounds thus prepared emitted blue light when excited at 365 nm and exhibited interesting photophysical properties.

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Michael addition of ethyl nitroacetate on α,β-unsaturated ketones followed by Nef oxidation under hydrolytic conditions yields γ-oxoacids instead of the corresponding α,δ-dioxoesters. A concerted decarboxylation step is proposed on the basis of computational results. Finally, conversion of the γ-ketoacids thus prepared into 1H-pyrrol-2(5H)-ones by reaction with primary amines under Paal-Knorr conditions is also reported.

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