Photochemistry of diethynyl sulfides: a cycloaromatization for the formation of five-membered rings.
The first five-membered ring cycloaromatization reaction has been demonstrated. Photoirradiation of bis(phenylethynyl) sulfide in hexanes/1,4-cyclohexadiene produces 3,4-diphenylthiophene through the presumed intermediacy of 2,5-didehydrothiophene. In addition, phenylacetylene is produced in this reaction consistent with competing direct carbon-sulfur cleavage. For reactions in ethanol or 2-propanol production of the thiophene is accompanied by the formation of phenylacetylene and a thionoester of the corresponding alcohol. Thiophene products also result from the irradiation of other diethynyl sulfides. [reaction: see text]
Lewis
Kevin D
KD
Department of Chemistry and the Macromolecular Science and Engineering Program, The University of Michigan, Ann Arbor, MI 48109-1055, USA.
Wenzler
David L
DL
Matzger
Adam J
AJ