New Asymmetric Reactions Using (S)-2-Aminomethylpyrrolidine Derivatives MASATOSHI ASAMI
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University of Tokyo, Department of Chemistry, Faculty of Science, Tokyo, Japan 113
A new chiral auxiliary reagent, (S)-2-substituted-amino -methylpyrrolidine 1, has been designed based on the fundamental assumption that a conformationally restricted cis-fused five -membered bicyclic structure would be effective for asymmetric in duction. The effectiveness of the new reagent was realized in the following highly stereoselective reaction: Asymmetric reduction of prochiral ketones. A chiral hydride reagent formed by treating the chiral diamine 1 with LiAlH was postulated to assume a cis-fused five-membered bicyclic ring structure 2. Highly enantiomerically pure alcohols were obtained when the reaction was carried out in ether at low temperature (-100°C) by employing diamines 1 having 2,6-xylyl or phenyl substituents on nitrogen. 4
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α-Tetralone 0097-6156/82/0185-0263$05.00/0 © 1982 American Chemical Society
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In Asymmetric Reactions and Processes in Chemistry; Eliel, E., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.
264
ASYMMETRIC REACTIONS AND
PROCESSES IN CHEMISTRY
Asymmetric synthesis of optically active aldehydes.
The
idea was extended to the synthsis of various synthetically useful optically active aldehydes utilizing aminals having a similar rigid structure as 2. The f i r s t example is an asymmetric
1,2-
addition of Grignard reagents to a chiral keto aminal leading to various
α-hydroxyaldehydes.
The u t i l i t y of the aminal structure
was also shown in an asymmetric 1,4-addition of Grignard reagents Downloaded by GEORGETOWN UNIV on August 26, 2015 | http://pubs.acs.org Publication Date: April 28, 1982 | doi: 10.1021/bk-1982-0185.ch019
to an aminal 3, prepared from the diamine 1 (R=Ph) and fumaraldehydic acid methyl ester.
Various 3-alkylsuccinaldehydic acid
methyl esters were thus obtained with high optical yields.3
Another highly enantioselective addition was achieved by using the chiral aryllithium derived from 4. lithium compound assumes structure 5.
Presumably the
Highly optically pure
lactols 6 were obtained by i t s reaction with aldehydes.
The
resulting lactols 6 were successfully converted to optically active 3-alkylphthalide, e.g., (S)-3-butylphthalide, an essential o i l of celery.4
In Asymmetric Reactions and Processes in Chemistry; Eliel, E., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.
ASAMi
(S)-2-Aminomethylpyrrolidine
Derivatives
265
(S)-3-Butylphthalide
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Literature Cited 1. a) Mukaiyama, T., Asami, M., Hanna, J., Kobayashi, S. Chem. Lett., 1977, 783. b) Asami, Μ., Ohno, H., Kobayashi, S., Mukaiyama, T. Bull. Chem. Soc. Jpn., 1978, 51, 1864. c) Asami, M., Mukaiyama, T. Heterocycles, 1979, 12, 499. 2. See Mukaiyama, T., article in this volume. 3. Asami, M., Mukaiyama, T. Chem. Lett., 1979, 569. 4. Asami, M., Mukaiyama, T. ibid., 1980, 17. RECEIVED December 21, 1981.
In Asymmetric Reactions and Processes in Chemistry; Eliel, E., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.
