Photoreactions of trans-1-o-Hydroxyphenyl-2-phenylcyclopropane.
The photochemistry of trans-1-o-hydroxyphenyl-2-phenylcyclopropane, trans-1, was studied under a variety of experimental conditions. Direct irradiation through quartz in cyclohexane gave rise mainly to ring-expanded products, 2-phenyl-3,4-dihydro-2H-benzopyran, 2, 2-benzyl-2,3-dihydrobenzofuran, 3, and 1-o-hydroxyphenylindan, 4. The major products, 2 and 3, are rationalized by intramolecular proton transfer. However, a significant fraction of 3 is formed via ring-opening to cinnamylphenol, 5. An additional product, o-(alpha-cyclohexylmethyl)phenol, 7, suggests fragmentation of trans-1 and (formal) insertion of o-hydroxyphenylcarbene into cyclohexane. Direct irradiation in methanol produced methanol adducts 8 and 9 instead of 2, 3, 4, or 7. Finally, acetone-sensitized irradiation of trans-1 resulted in geometric isomerization to cis-1; this result can be rationalized via a biradical intermediate.
Delgado
Julio
J
Departamento de Química/Instituto de Tecnología Química UPV-CSIC, Universidad Politécnica de Valencia, Camino de Vera s/n, Apdo 22012, 46071 Valencia, Spain, and Department of Chemistry, Wright-Rieman Laboratories, Rutgers University, New Brunswick, New Jersey 08854-8087.
Espinós
Amparo
A
Jiménez
M. Consuelo
MC
Miranda
Miguel A.
MA
Roth
Heinz D.
HD
Tormos
Rosa
R