- Photochemistry of 1-Alkoxy- and 1-(Benzyloxy)-9,10-anthraquinones in Methanol: A Facile Process for the Preparation of Aldehydes and Ketones
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The facile production of acid sensitive aldehydes and ketones via photochemical intramolecular δ-hydrogen atom transfer in 1-alkoxy- and 1-(benzyloxy)-9,10-anthraquinones (1) was investigated.Irradiation of 1 in argon purged methanol generates the primary photoproducts, 1-(RCH(OMe)O)- and 1-(ArCH(OMe)O)-9,10-anthrahydroquinones (2), respectively.Upon exposure to air, the intermediate anthrahydroquinone is rapidly converted to the corresponding aldehyde and 1-hydroxy-9,10-anthraquinone (3), which can be recycled.Aldehydes containing an acetal or ketal were prepared in high yields using this photoprocess.Apparent rate constants for the photodemethylation of 1-methoxy-2-X-9,10-anthraquinones (X = H, Me, Et, Pr, i-Bu, and benzyl) were measured and found to vary by a factor of 10 separating the slowest anthraquinone (X = H) and the fastest (X = benzyl), indicating a strong dependency upon the size of the substituent at the 2-position.These rate constants are ascribed to equilibrium populations of conformers in the geometry required for the reaction in the n,?* triplet state.
- Blankespoor, Ronald L.,Smart, Robert P.,Batts, Eric D.,Kiste, Alan A.,Lew, Rebecca E.,Vliet, Marc E. Vander
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p. 6852 - 6859
(2007/10/03)
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- Photochemistry of 1-alkoxy- and 1-(benzyloxy)-9,10-anthraquinones in methanol: a δ-hydrogen atom abstraction process that exhibits a captodative effect
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The photochemistry of a variety of 1-alkoxy- and l-(benzyloxy)-9,10-anthraquinones in methanol has been examined. In the absence of oxygen the primary photoproducts of these reactions are 9,10-anthrahydroquinones with MeOCH2O and ArCH(OMe)O gro
- Blankespoor, Ronald L.,De Jong, Randall L.,Dykstra, Robert,Hamstra, Daniel A.,Rozema, David B.,Vanmeurs, Derek P.,Vink, Paul
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p. 3507 - 3513
(2007/10/02)
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