| abstract |
The invention relates to a method for the photochemi-cal isomerisation of organic compounds, in particular for the photochemical conversion of tachysterol compounds into previtamin D compounds and of trans-vitamin D compounds into cis-vitamin D compounds, under the influence of radiation, by exposing a solution of the organic compound to be converted in the presence of a non-polymeric photosensitizer to light with approx. 300-1,000 nm wavelength, and by then isolating the resulting product, wherein a substituted thiophene derivative having a substantial absorption in said wavelength region is used as the photosensitizer. The invention also relates to a new photosensitizer to be used for said isomerisation reaction. |