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DOI: 10.1055/s-2001-15076
Intramolecular [2+2] Photocycloaddition of Bichromophoric Derivatives of 3,5-Dihydroxybenzoic Acid and 3,5-Dihydroxybenzonitrile
Publication History
Received
18 December 2000
Publication Date:
24 September 2004 (online)


Abstract
The irradiation of 3-alkenyloxy-5-hydroxybenzoic acid derivatives 1a-d yields highly functionalized alkyloxyenone derivatives when the reaction is carried out in the presence of acid. A higher reactivity is observed for the corresponding 3-alkenyloxy-5-hydroxybenzonitrile compounds 7a, b, which also react in neutral reaction media. In the first step of the reaction, a [2+2] photocycloaddition occurs. The following steps, leading to stable final products, need acid catalysis in the case of the substrates 1a-d. The irradiation of the benzonitrile derivative 7b also furnishes the side product 9, which results from a [2+3] photocycloaddition.
Key words
photochemistry - cycloaddition - arenes - acidic reaction medium - herbicides