1
i SOPRENOIDS
Isoprenoids, perhaps more than any other class of organic compounds,
are associated in the minds of many biological and physical scientists with
the chemistry of natural products. These compounds therefore form a suitable beginning for our discussion.
Wallach (1887) first recorded the remarkable observation that a distinct
group of naturally occurring substances may be formally derived from
branched five-carbon units. The ensuing theory that these compounds, the
terpenes or perhaps more accurately the terpenoids, are biosynthesized from
branched five-carbon modules was first stated by Ruzicka and Stoll (1922).
Ruzicka's theory has been one of the most fruitful in organic chemistry. It has
inspired and guided an incredible amount of imaginative research in structural
determination and in organic synthesis—in vitro and in vivo. Beyond that,
much research in physical-organic chemistry, in the area of molecular rearrangements in particular, has been sparked and sustained by the monoterpenes of the camphane series. In their own right, the terpenoids have long
mirrored the development of organic chemistry. At the outset, as extractives
of terrestrial plants, the terpenoids were prized for their pleasant aroma.
For many years they were an interesting subject for academic research. More
recently, with the advent of sophisticated methods of isolation, separation,
and structural elucidation, terpene research has expanded greatly and has
established these compounds as one of the most diverse and intriguing groups
of natural products. Little wonder then that isoprenoid substances have been
isolated not only from their traditional substrates, essential oils of vegetable
1
i SOPRENOIDS
Isoprenoids, perhaps more than any other class of organic compounds,
are associated in the minds of many biological and physical scientists with
the chemistry of natural products. These compounds therefore form a suitable beginning for our discussion.
Wallach (1887) first recorded the remarkable observation that a distinct
group of naturally occurring substances may be formally derived from
branched five-carbon units. The ensuing theory that these compounds, the
terpenes or perhaps more accurately the terpenoids, are biosynthesized from
branched five-carbon modules was first stated by Ruzicka and Stoll (1922).
Ruzicka's theory has been one of the most fruitful in organic chemistry. It has
inspired and guided an incredible amount of imaginative research in structural
determination and in organic synthesis—in vitro and in vivo. Beyond that,
much research in physical-organic chemistry, in the area of molecular rearrangements in particular, has been sparked and sustained by the monoterpenes of the camphane series. In their own right, the terpenoids have long
mirrored the development of organic chemistry. At the outset, as extractives
of terrestrial plants, the terpenoids were prized for their pleasant aroma.
For many years they were an interesting subject for academic research. More
recently, with the advent of sophisticated methods of isolation, separation,
and structural elucidation, terpene research has expanded greatly and has
established these compounds as one of the most diverse and intriguing groups
of natural products. Little wonder then that isoprenoid substances have been
isolated not only from their traditional substrates, essential oils of vegetable
1