The 3-alkyl-2,2-dimethyl-4-(tert-butyl)-2H-thietes 9a–c were obtained in several steps from the corresponding, newly synthesized, 3-alkyl-2-(tert-butyl)thiophenes 5a–c. Irradiation (254nm) of these tetraalkylated four membered S-heterocycles leads to a photostationary equilibrium with enethiones 10a–c (thiete/enethione 3:1).