Synthesis and Photochemistry of 2,2-Dimethyl-3(H)-thiophenone, a Ketonic Tautomer of 3-Hydroxythiophene

Article abstract of DOI:10.1002/hlca.19840670528

On irradiation (λ = 366 nm), the 4-thia-2-cyclopentenone 3a behaves in complete analogy to the oxa-enone 3c undergoing regio- and stereospecific cyclodimerization, regiospecific cycloaddition with 2-methylpropene and cycloaddition with 2,3-dimethyl-2-butene to afford cyclobutane derivatives.In contrast, the 4-aza-2-cyclopentenone 3b does not undergo the above-mentioned reactions but only slow photocomposition.