Reactions to form six-membered rings

Dicarbonyl compounds can undergo intramolecular reactions to form six-membered rings. 

After that, the same group also reported catalytie, enantioselective hydroacylations of AT-allylindole-2-carboxaldehyes and N-allylpyrrole-2-car-boxaldehydes (Scheme 8.12)/ These hydroacylations occur smoothly to form dihydropyridoindolones and dihydroindolizinones in moderate to high yields and excellent enantioselectivity from a variety of indole and pyrrole substrates and represent the first example of highly enantioselective, transition metal-catalyzed hydroacylation reactions to form six-membered-rings in the absence of chelation assistance. 

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