Synthesis of trans-Vitamin D2

Abstract

The synthesis of the trans-vitamin D2, via its sulfur dioxide adduct, is presented here. The trans isomer of vitamin D2 will be used as a model molecule, for the study of the photo-sensitized photoisomerization of vitamin D2 from its trans isomer to the naturally occurring, biologically active, cis isomer. The photoisomerization study will help advance the synthesis of a cis-vitamin D5 intermediate, subject to a different, multistep synthesis of 1?-hydroxyvitamin D5, a cancer chemopreventive agent. The synthesized trans-vitamin D2 was purified by column chromatography and characterized by 1H-NMR spectrometry. The overall chemical yield was of 71%.