The phototransposition reactions of thiophene- carbonitriles were shown to occur via the intermediate formation and isomerisation of 5-thiabicyclo[2˙1˙0]pent- 2-enes . Thus, irradiation of thiophene-3-carbonitrile in cyclohexane gave 5-thiabieyelo[2˙1˙0]pent-2-ene-2-carbonitrile as the primary photochemical product. Further irradiation produced thiophene-2-carbonitrile. The reaction was reversible, Addition of furan to 5-thiabicyclo[2˙1˙0]pent-2-ene-2- carbonitrile yielded a mixture of exo and endo-10,4-oxa thiatetracyclo[5˙2˙1˙0,sup>2,6</sup>˙ 0sup>3,5</sup>]dec-8-ene-2-carbonitrile. These two adducts were similarly formed upon irradiation of either thiophene-2 or 3-carbonitrile in furan.

Thesis (M. Phil.)--University of Hong Kong, 2008. / Also available in print.