The application of photochemical approaches to synthesis of heterocycles and strained carbon-carbon bonds will be expanded. Photoextrusion of SO2 and H2O from sulfones and oxazines has proven to be a high yield, convenient process for several examples such as pyrroles and cyclophanes. These derivatives are available via 4 to 6 step synthetic sequences in which photoextrusion is a key step. Additional pyrroles will be constructed by this same methodology. New chromophores will be explored for the photoextrusion process. These include alpha, beta-unsaturated ketones and homo-allylic aryl systems. Other free radical stabilizing groups will be used in conjunction with the photoextrusion studies including vinyl, cyano, and methoxy derivatives. These studies will allow a sharper view of the extent and limitations of the photoextrusion process as a synthetic method and will serve as model systems for construction of the steroid framework proposed earlier. The thermal and photochemical rearrangements of several non-conjugated pi-systems will be studied in detail. The photochemical study will provide insight into the mechanism of intersystem crossing, important for the photochemical construction of cyclopropyl ketones from beta, gamma-unsaturated ketones. The thermal rearrangement shows promise as a route to stereochemically defined bicyclo(4.3.0)nonanes and potentially to bicyclo(4.4.0)decanes with highly functionalized rings. The synthetic potential as precursors to terpenes is envisaged.