PHOTOCHEMISTRY OF CONJUGATED TRIENES - VITAMIN-D REVISITED

A survey is given of various factors and conditions that affect the ph otoreactivity and photoproduct distribution of conjugated trienes, suc h as ground-state rotameric equilibrium, non-planarity of the chromoph ore, wavelength of irradiation, solvent and temperature. The effect of changes in ground-state conformation and geometry, caused by substitu tion or variation of solvent or temperature, usually appears to be mor e important and more easily predictable than excited state effects.