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Book Review Natural Products. A Laboratory Guide. 2nd Edition. By R. Ikan

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Natural Products. A Laboratory Guide. 2nd Edition. By R.
I k m . Academic Press, New York, 1991. XIV, 360 pp.,
hardcover $54.95. -ISBN 0-12-370551-7
Most specialist books are either cheaply produced or too
expensive or, in the worst cases, both. The one reviewed here
is not cheaply produced; it is typeset in a clear style, printed
on good paper, and solidly bound. But what purpose does it
serve? More on this later.
The main content of the 17 chapters (about 350 pages altogether) consists of descriptions of 33 isolations of natural
products, of which 26 are from the plant kingdom, five from
the animal kingdom, and two others. In addition 15 conversion o r breakdown reactions and five total syntheses are
described. Also included are experimental data on 24 chromatographic separations and six other laboratory processes
(color reactions, formation of inclusion complexes, separation of racemates, etc.).
The contents are arranged under four main compound
classes: acetogenins. carbohydrates. isoprenoids, and nitrogen compounds. These are further subdivided; for example,
the acetogenins are divided into flavones, lipids, lignans,
quinones. and phloroglucinols. Each chapter begins with an
introduction and ends with questions and a list of recommended books. The middle part describes the individual experiments relating to the subject of the chapter.
Each introduction describes the relevant group of natural
products and explains its subdivisions. For example, steroids
are subdivided into sterins. bile acids, steroid hormones,
compounds with cardiac activity, and sapogenins. On the
whole these introductions are very detailed and well illustrated with formula diagrams, although regrettably these are
often shown as “flat” structures that are stereochemically
ambiguous. These introductions are, ofcourse, no substitute
for reading up on natural products chemistry in the relevant
textbooks, especially since they do not deal at all with the
important aspect of biosynthesis. Nevertheless, they are suitable as a first introduction o r for revision, and are presumably meant to be no more than that.
The questions are intended to serve as revision of what has
been learnt, but the chemical aspects are not adequately covered. Only rarely does one find questions about reactions or
understanding of the principles; instead the emphasis is on
names and definitions (“What is ...?” or “Describe ...”). It is
doubtful whether this style is suitable as a preparation for
examinations.
The descriptions of experiments contain many old favorites, such as Gattermann’s methods for the isolation of caffeine from tea and of heme from blood. However, some
micropreparations are also included, where the emphasis is
not so much on isolating significant quantities as on chromatographic investigations, as in the isolation of pteridines
from fruit-flies. Finally, to complete the picture, there are
some examples of conversions (e.g., cholesterol to
cholestenone. which again is old hat) and total syntheses
(e.g., mescalin---was this really necessary?). These experimental descriptions again follow a consistent pattern under
standard headings: introduction, principle of the method,
apparatus, materials. time required, and execution. The latter usually also includes information on yield, physical properties, test reactions and derivatives, spectroscopic data, and
literature references. The latter especially makes it evident
that the original edition is now 25 years old.
Some important items that have been added since the first
edition are the spectroscopic data given for most of the end
products. and details of the flash chromatography of essential oils. HPLC of carotenoids, RP-HPLC of amino acids,
HPTLC of carbohydrates. experiments on geoporphyrins,
yeast RNA, and the synthesis and breakdown of alkaloids
and steroids.
Time and again one asks “Is this necessary?” Not because
of the errors. which are very few -for example. in the formula diagrams on pages 201 and 252, in nomenclature (the
correct names are citral, not geranial, and sabinene. not
sabonene), and on page 240 where the impression is given
that strychnine can be extracted from ground-nuts. These
are pardonable sins, but more serious faults to my mind are
the unnecessarily detailed descriptions of experiments
(pp. 280f., preparation of silica gel layers on glass rods and
test-tubes for thin-layer chromatography), and sketches of apparatus whose poor print quality alone indicates that they
have probably been simply photocopied (p. 197, apparatus for
UV irradiation, and p. 200. where the flash chromatography
sketch is clearly identical to that in Still’s original publication).
Who should buy this book? Obviously it tries to achieve
too much. The whole of natural products chemistry, from
isolation and structure determination through conversions
to the total synthesis of natural products - a subject that
should certainly also include biosynthesis -cannot be compressed into 350 pages. If the subtitle “A Laboratory Guide”
is intended seriously, a good deal of this could be left out.
and perhaps also some of the old familiar stuff could be
sacrificed in favor of up-to-date procedures. At this price
students are hardly likely to buy the book, and natural products chemists will find in it little that they d o not already have
in other sources; however. interested scientists from neighboring disciplines can obtain from it a concise impression of
the variety of natural products chemistry.
Horst C. U x r
Fachbereich Organische Chemie
der Universitdt-Gesamthochschule Siegen (FRG)
Nucleophilic Aromatic Displacement. The Influence of the
Nitro Group. (Series: Organic Nitro Chemistry Series). By
E Terrier. VCH Publishers, New York/VCH Verlagsgesellschaft. Weinheim, 1991. XI, 460 pp., hardcover
DM 239.00.- ISBN 0-89573-31 2-913-527-26746-8
The attention of modern organic chemistry is directed
mostly towards control of the stereochemistry of organic
reactions, synthesis of natural products, and especially towards life processes. The chemistry of aromatic compounds,
particularly nucleophilic substitution in aromatic rings, is
presently “out of fashion” in academic research. There are
some reasons for such an attitude; nevertheless, since the
majority of products of organic chemical industry contain
aromatic carbo- or heterocyclic rings, the chemistry of arenes is still of great importance. Moreover, contrary to the
common opinion, it also offers a significant intellectual challenge and an interesting field for discoveries.
In this situation the appearance of the monograph by
Franqois Terrier is very timely and welcome. In a relatively
short volume the author discusses many important effects of
the nitro group on the reactivity of aromatic compounds
with nucleophilic agents. Thus, such problems as the kinetics
and thermodynamics of the formation of a-adducts, classical
nucleophilic aromatic substitution of leaving groups, and
many variants of nucleophilic substitution of hydrogen,
photosubstitution, etc., are thoroughly discussed, and a rich
selection of examples and references is given. As one might
expect, the author’s own preferences and interests flavor the
book to a noticeable extent. Physicochemical and mechanistic problems are discussed in more depth than practical
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