D. A. Evans Isoprene: Building Block of Nature(2) Chem 206 Classification of terpenes a Terpene Biosynthesis tail monoterpenes: 10 C-atoms(2 isoprene units sesquiterpenes: 15 C-atoms(3 isoprene units)i There are two isoprene units which are used to build up terpenes 2-methyl-1, 3-butadiene 20 C-atoms(4 iso 30 C-atoms(6 is 人~ 1 yme Yr-dimethylallyl pyrophosphate 00 R0--0-1-0H≡ROXR+o H3≡RoTs menthol camphor nature's leaving group chemist's leaving group 9 The basic process: alkene addition to electrophiles -0X sex attractant pheromone of the cinnamide DMAP HB otene natural rubber geraniol Practice: Recognize the isoprene units in the above structures 32A-03 terpenes212/17998:00AM≡ ≡ n Chem 206 geraniol H2O/OH￾geranyl pyrophosphate -HB -OX￾B- DMAP The basic process: alkene addition to electrophiles: tosylate: chemist's leaving group ROX ROTs pyrophosphate: nature's leaving group γ,γ-dimethylallyl pyrophosphate (DMAP) isopentenyl pyrophosphate (IPP) enzyme There are two isoprene units which are used to build up terpenes: Isoprene : Building Block of Nature (2) 2-methyl-1,3-butadiene isoprene head tail geraniol citronellol two components in rose oil menthol camphor sex attractant pheromone of the American cockroach cinnamolide antifungicide ß-carotene natural rubber monoterpenes : 10 C-atoms (2 isoprene units) sesquiterpenes : 15 C-atoms (3 isoprene units) Classification of terpenes h t h t ■ Terpene Biosynthesis Practice: Recognize the isoprene units in the above structures. D. A. Evans diterpenes : 20 C-atoms (4 isoprene units) triterpenes : 30 C-atoms (6 isoprene units) Me OH OH OH O O O O O Me OX OX Me Me ROP O O P O O OH ROS O O CH3 O OX Me Me Me Me CH2 OX Me Me Me Me OX H H Me Me OX Me Me Me Me OH H2C Me Me O O O H 32A-03-terpenes-2 12/17/99 8:00 AM