- PROCESS FOR PREPARING AMINES AND A CARBOXAMIDE THEREOF
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Chiral, secondary amines of the formula (I) or (II), where R01, R02 and R03 are each, independently of one another, C1-C4-alkyl, R04 is C1-C4-alkyl, C1-C4-alkoxymethyl or C1-C4-alkoxyethyl, and * indicates predominantly one configurational isomer, can be obtained by hydrogenation of corresponding ketimines in the presence of iridium complexes with chiral ferrocene tetraphosphines in which a secondary phosphine group and 1-secondary phosphinalk-1-yl are bound to each cyclopentadienyl ring in ortho positions.
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Page/Page column 23
(2010/02/15)
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- Chemoenzymatic synthesis of the chiral herbicide: (S)-metolachlor
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A chemoenzymatic approach for the production of (5)-metolachlor, one of the most widely used herbicides, has been developed. The starting material (S)-N-(2-ethyl-6-methylphenyl)alanine was obtained by the use of lipase-catalyzed hydrolytic kinetic resolution. Under the optimal conditions, the good activity and excellent enantioselectivity of lipase B from Candida antarctica (CAL-B, E > 100) are achieved in diethyl ether - water (15% v/v), which is about 9.7-fold more enantioselective than that in a pure buffered aqueous solution (E = 12.1). After a simple extraction procedure is used to separate the acid product from the remaining ester, the remaining ester is racemized, providing the basis for the continuous resolution process. Then (S)-metolachlor is synthesized by a simple chemical method using the enantiomerically pure (S)-acid.
- Zheng, Liangyu,Zhang, Suoqin,Wang, Fang,Gao, Gui,Cao, Shugui
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p. 1058 - 1063
(2007/10/03)
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- ENANTIOSELECTIVE SYNTHESIS OF OPTICALLY ACTIVE METOLACHLOR VIA ASYMMETRIC REDUCTION
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Optically active metolachlor was prepared by chloroacetylation of the corresponding amine obtained by asymmetric reduction of the requisite imine with the chiral hydrides, such as Itsuno's reagent (4), Corey's reagent (5) and K glucoride (6).
- Cho, Byung Tae,Chun, Yu Sung
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p. 337 - 340
(2007/10/02)
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