Benzoyl radicals from (hetero)aromatic aldehydes. Decatungstate photocatalyzed synthesis of substituted aromatic ketones.
Benzoyl radicals are generated directly from (hetero)aromatic aldehydes upon tetrabutylammonium decatungstate ((n-Bu(4)N)(4)W(10)O(32)), TBADT) photocatalysis under mild conditions. In the presence of alpha,beta-unsaturated esters, ketones and nitriles radical conjugate addition ensues and gives the corresponding beta-functionalized aryl alkyl ketones in moderate to good yields (stereoselectively in the case of 3-methylene-2-norbornanone). Due to the mild reaction conditions the presence of various functional groups on the aromatic ring is tolerated (e.g. methyl, methoxy, chloro). The method can be applied to hetero-aromatic aldehydes whether electron-rich (e.g. thiophene-2-carbaldehyde) or electron-poor (e.g. pyridine-3-carbaldehyde).
Ravelli
Davide
D
Department of Organic Chemistry, University of Pavia, Viale Taramelli 10, 27100 Pavia, Italy.
Zema
Michele
M
Mella
Mariella
M
Fagnoni
Maurizio
M
Albini
Angelo
A
D000447:Aldehydes / Q000737:chemistry*; D002384:Catalysis; D005609:Free Radicals / Q000138:chemical synthesis / Q000737:chemistry; D007659:Ketones / Q000138:chemical synthesis* / Q000737:chemistry*; D015394:Molecular Structure; D009570:Nitriles / Q000737:chemistry; D010777:Photochemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D017973:Tungsten Compounds / Q000737:chemistry*
D000447:Aldehydes; D005609:Free Radicals; D007659:Ketones; D009570:Nitriles; D000644:Quaternary Ammonium Compounds; D017973:Tungsten Compounds; C009405:tetrabutylammonium