(E Z)-ISOMERIC CAROTENES

Selected examples of new developments dealing with the preparation of (Z)-isomeric carotenes are presented. Some unpublished results on the synthesis and characterization of geometrical isomers of beta,beta-car otene, (rac)-beta,epsilon-carotene and psi,psi-carotene (lycopene) are included. Thermal isomerization of (all-E)-carotenes and the signific ance of (Z)-isomers in carotene biosynthesis are addressed.