Synthesis of pyridobenzopyrans

O -alkylation of salicylaldehyde with the appropriate alkynyl halides followed by Wadsworth - Emmons olefination affords the required substrate for the intramolecular Diels - Alder cyclisation
poster 3a

R = H, Ph

Diels - Alder cyclisations
poster 3b

All cyclisations proceeded smoothly to give the desired tricylic adduct in approximately 40% overall yield
Note that the cinnamyl bromide derived product fully aromatised during the reaction.

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