Sensitized photocyclodimerization of αβ-unsaturated cyclic sulfones. Crystal structural analyses of the photodimers of 2-sulfolene and thia-2-cyclohexene-1,1-dioxide.
The reactivity of five- and six-membered unsaturatedcyclic sulfones in sensitized photocyclodimerization depends on position and substitution of the doublebond. Thus, 2-sulfolene (1) and its six-membered analogue thia-2-cyclohexene-1,1-dioxide (3) photodimerize to yield each three products, 5, 6, 7 and 9, 10, 11, respectively, of which only 7 and 10 are analogous. However, 3-methyl-2-sulfolene (1a)