Structure and synthesis of naturally occurring anhydrovitamin A2

The structure of naturally occurring anhydrovitamin A2 was elucidated as 3-hydroxyanhydroretinol from study of its u.v.--visible, i.r., n.m.r. and mass spectra. The structure has been confirmed by a chemical synthesis. Saccobranchus fossils, a freshwater fish, can convert 3-hydroxyretinol into 3-hydroxyanhydroretinol, which in turn is converted into-3-dehydroretinol. Chemical conversion of 3-hydroxyretinol into 3-dehydroretinol was also carried out.