Acid catalyzed intramolecular [2+2] photocycloaddition of 3,5-dihydroxybenzoic acid derivatives
作者:Norbert Hoffmann、Jean-Pierre Pete
DOI:10.1016/s0040-4039(98)00993-9
日期:1998.7
3-alkenyloxy-5-irydroxybenzoic and the corresponding 3-alkenyloxy-5-methoxybenzoic acid derivatives 1 – 4 in the presence of small quantities of H2SO4 produces highly functionalized alkyloxyenones 6 – 8 in good or moderate yields. The products are explained via an acid catalyzed transformation of the primary [2+2] photocycloadducts.
Intramolecular [2+2] Photocycloaddition of Bichromophoric Derivatives of 3,5-Dihydroxybenzoic Acid and 3,5-Dihydroxybenzonitrile
作者:Norbert Hoffmann、Jean-Pierre Pete
DOI:10.1055/s-2001-15076
日期:——
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.