302
3. Lynn, D. E., Miller, S. G. & Oberlander, H., Estab-
Extended Summaries: 9th Pesticide Chemistry Congress
J. E. Casida. Elsevier Science Publishers, Amsterdam,
Oxford, New York, 1990, pp. 251È7.
20. Smagghe, G. & Degheele, D., Biological activity and
receptor binding of ecdysteroids and the ecdysteroid
agonists RH 5849 and RH 5992 in imaginal wing discs of
Spodoptera exigua (Lepidoptera: Noctuidae). Eur. J.
Entomol., 92 (1995) 333È40.
21. Oberlander, H. & Tomblin, C., Cuticle deposition in ima-
ginal disks: E†ects of juvenile hormone and fat body in
vitro. Science (W ashington), 177 (1972) 441È2.
22. Silhacek, D. L. & Oberlander, H., Time-dosage studies of
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discs: Induction of newly synthesized proteins by 20-
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2589È93.
4. Lynn, D. E. & Oberlander, H., The establishment of cell
lines from imaginal wing discs of Spodoptera frugiperda
and Plodia interpunctella. J. Insect Physiol., 29, (1983)
591È6.
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for research in physiology, development, and genetics. In
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Press, New York, 1987, vol. 5, pp. 187È207.
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cell lines as tools for studying ecdysteroid action.
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43È53.
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developmental capacities of insect cell lines. In Insect Cell
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Enantioselective Catalysis for Agrochemicals:
Synthetic Routes to (S)-Metolachlor,
(R)-Metalaxyl and (aS,3R)-Clozylacon
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Felix Spindler, Benoit Pugin, Hanspeter Buser, Hans-
Peter Jalett, Ulrich Pittelkow & Hans-Ulrich Blaser*
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Shaaya, E., Arch. Insect. Biochem. Physiol., 18 (1991) 219È
27.
Novartis Services AG, Catalysis
CH-4002 Basel, Switzerland
& Synthesis Services, R-1055.6
Abstract: The application of enantioselective catalytic
methods for the technical preparation of chiral agrochemicals
is illustrated for three active ingredients of the acylanilide
type. The key step for the technical synthesis of the herbicide
(S)-metolachlor is the enantioselective hydrogenation of an
imine
intermediate
using
a
novel
iridium
fer-
rocenyldiphosphine catalyst with an unprecedented high
activity and 80% ee. (R)-metalaxyl and (aS,3R)-clozylacon were
synthesized via the enantioselective hydrogenation of corre-
sponding enamide precursors with Rh and Ru/binap catalysts
with [95% and 99% enantiomeric purity, respectively. (
1998 Society of Chemical Industry
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I. & Shaaya, E., Chitin synthesis in Spodoptera frugiperda
wing imaginal discs: I. ChlorÑuazuron, diÑubenzuron, and
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[14C] N-acetyl-D-glucosamine. Arch. Insect Biochem.
Physiol., 25 (1994) 245È58.
Pestic. Sci., 54, 000È000 (1998)
Key words: Chiral acyl anilides; chiral switch; enantio-
selective hydrogenation; (R)-metalaxyl; (S)-metolachlor; (aS,
3R)-clozylacon
14. Zimowska, G., Miko¡ajczyk, P., Silhacek, D. L. & Ober-
lander, H., Chitin synthesis in Spodoptera frugiperda wing
imaginal discs. II. Selective action of chlorÑuazuron on
wheat germ agglutinin binding and cuticle ultrastructure.
Arch. Insect Biochem. Physiol., 27 (1994) 89È108.
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doptera. Science (W ashington), 241 (1988) 470È2.
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E†ects on a Drosophila cell line. Science (W ashington), 241
(1988) 467È9.
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of RH 5849, a nonsteroidal ecdysteroid mimic, on Plodia
interpunctella (Hubner) in vivo and in vitro. Arch. Insect
Biochem. Physiol., 15 (1990) 201È12.
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steroidal ecdysteroid agonists: Tools for the study of hor-
monal action. Arch. Insect Biochem. Physiol., 28 (1995)
209È23.
1
Introduction
The biological properties of chiral agrochemicals are
often strongly related to the absolute conÐguration.1 As
a consequence, the technical synthesis of pure or
enriched enantiomers is of growing importance in the
modern agrochemical industry. A promising technology
for very efficient asymmetric syntheses is the application
of chiral catalysts but, in the end, the best overall syn-
thesis will be chosen for commercial production. For a
technically feasible catalytic process, high enantio-
selectivity is not the only prerequisite; other factors
such as catalyst productivity, catalyst activity, catalyst
stability, availability and quality of the starting
material, etc., can be even more important from a pro-
duction point of view.2 Catalyst productivity, expressed
19. Wing, K. D. & Aller, H. E., Ecdysteroid agonists as novel
insect growth regulators. In Pesticides and Alternatives, ed.
* To whom correspondence should be addressed.
E-mail: hans-ulrich.blaser=sn.novartis.com