Photo-Diels-Alder Cycloaddition Reactions of Aromatic Compounds

1 Photo-Diels-Alder Cycloaddition Reactions of Aromatic Compounds 

Indole 17 undergoes photo-induced radical cation Diels-Alder reaction with cyclohexa-1,3-diene 18 in the presence of triphenylpyrylium tetrafluoroborate to give diastereoselective product 19 [33]. 

1-Acetyl naphthalene 24 on photoirradiation undergoes [4 + 2]-cycloaddition reaction with chiral electron acceptor alkene, (5)-(2-methoxy methyl-1- 

1-Diphenylethene derivative 28 (as electron donor) undergoes photo-[4 + 21-cycloaddition reaction with 1,4-dicyanobenzene (as electron acceptor) in the presence of phenanthrene sensitizer to give isoquinoline derivative 29 in a PET process. The reaction takes place in a highly polar exciplex and/or a contact radical ion pair generated in a PET process, followed by air oxidation [36]. 

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