Oxygen-Containing Fused Polycyclic Targets

Wang and coworkers have developed an enantioselective reaction that affords chiral 4//-chromenes starting from aliphatic alkynals 107 and 2-(F)-(2-nitrovinyl)-phenols 

It involves an initial Knoevenagel condensation between the dialdehyde and the pyran-2-one derivative to give 122, followed by a Michael addition of the enaminone that furnishes 123, a lactamization that leads to 124, and a final intramolecular 

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