Isoprene, isomeric chain unit structure

Factors Affecting the Isomeric Chain Unit Structure in Organolithium Polymerization of Butadiene and Isoprene... 

Morton M, Rupert JR. Factors affecting the isomeric chain unit structure in organolithium polymerization of butadiene and isoprene. In Bailey FE Jr editor. Initiation of Polymerization. ACS Symposium Series. Volume 212. Washington (DC) American Chemical Society 1983. p 283. 

The basic skeleton of isoprenoids may be modified by the introduction of a wide variety of chemical groups, by isomerization, shift of double bonds, methyl groups, etc. Hence a bewildering number of chemical structures arises. In addition compounds derived from other biogenic pathways may contain isoprene residues. For instance the K vitamins (D 8.1), ubiquinones (D 8.3), chlorophylls (D 10.1), plastoquinones, and tocopherylquinones (D 22.4) have isoprenoid side chains with up to ten isoprene units. Polyketides (D 3.3), alkaloids (D 8.4.2), and coumarins (D 22.2.2) may be substituted by dimethylallyl groups. The terpene residues are attached to nucleophilic sites, such as active methylene groups and phenolic oxygen atoms. 

---