Organic compounds -- part of the class 532-570 series – Organic compounds – Nitrogen attached directly or indirectly to the purine ring...
Patent
1998-12-03
2000-10-24
Shah, Mukund J.
Organic compounds -- part of the class 532-570 series
Organic compounds
Nitrogen attached directly or indirectly to the purine ring...
A01N 4360, C07D24144
Patent
active
061369772
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to processes for producing D(+)-2-[4-(6-chloro-2-quinoxalyloxy)phenoxy]propionic acid and D(+)-2-[4-(6-chloro-2-quinoxalyloxy)phenoxy]propionic acid esters derived from the propionic acid. The esters are useful as selective herbicides for foliage treatment for controlling gramineous weeds against broad leaf crop plants.
BACKGROUND ART
Nippon Kagaku Kaishi, p. 253, (1991) discloses a process for producing ethyl D(+)-2-[4-(6-chloro-2-quinoxalyloxy)phenoxy]propionate, which comprises reacting an alkali metal salt of 4-(6-chloro-2-quinoxalyloxy)phenol with ethyl L-2-chloropropionate. JP-A-7-278047 discloses a process for producing D(+)-2-[4-(6-chloro-2-quinoxalyloxy)phenoxy]propionic acid, which comprises reacting an alkali metal salt and/or an alkaline earth metal salt of 4-(6-chloro-2-quinozalyloxy)phenol with an alkaline earth metal salt of L-2-chloropropionic acid. Further, U.S. Pat. No. 4,687,849 discloses a process for producing 2-isopropylidene aminoxyethyl D(+)-2-[4-(6-chloro-2-quinoxalyloxy)phenoxy]propionate, which comprises reacting 2-isopropylidene aminoxyethyl L(-)-2-(p-toluenesulfonyl)oxypropionate with 4-(6-chloro-2-quinoxalyloxy)phenol, a process for producing 2-isopropylidene aminoxyethyl D(+)-2-[4-(6-chloro-2-quinoxalyloxy)phenoxy]propionate, which comprises reacting 2-isopropylidene aminoxyethyl D(+)-2-(4-hydroxyphenoxy)propionate with 2,6-dichloroquinoxaline, and a process for producing 2-isopropylidene aminoxyethyl D(+)-2-[4-(6-chloro-2-quinoxalyloxy)phenoxy]propionate, which comprises reacting D(+)-2-[4-(6-chloro-2-quinoxalyloxy)phenoxy]propionic acid chloride with 2-isopropylidene aminoxyethanol. Further, JP-B-7-25753 discloses a process for producing tetrahydrofurfuryl 2-[4-(6-chloro-2-quinoxalyloxy)phenoxy]propionate, which comprises reacting tetrahydrofurfuryl 2-bromopropionate with 2-(4-hydroxyphenoxy)-6-chloroquinoxaline, and JP-A-4-295469 discloses a process for producing 2-isopropylidene aminoxyethyl D(+)-2-[4-(6-chloro-2-quinoxalyloxy)phenoxy]propionate, which comprises an ester exchange reaction of ethyl D(+)-2-[4-(6-chloro-2-quinoxalyloxy)phenoxy]propionate obtained by a reaction of 2,6-dichloroquinoxaline with ethyl D(+)-2-(4-hydroxypheoxy)propionate.
The process disclosed in Nippon Kagaku Kaishi, p. 253 (1991) is not necessarily industrially satisfactory for producing a product of high optical purity.
Whereas, JP-A-7-278047 discloses that in the reaction of an alkali metal salt of 4-(6-chloro-2-quinoxalyloxy)phenol with an alkali metal salt of L-2-chloropropionic acid, the reaction is terminated at a conversion of about 50% due to a side-reaction, and the yield is very low. The same publication also discloses that a barium salt is particularly preferred as the alkali salt and/or the alkaline earth metal salt. However, if the barium salt is used, there is a problem that a large amount of barium-related compounds as typical by-products is formed, and it has been desired to develop a more efficient production process.
DISCLOSURE OF THE INVENTION
The present inventors have conducted an extensive study to solve the above-mentioned problems and as a result, have accomplished the present invention. Namely, the present invention provides a process for producing D(+)-2-[4-(6-chloro-2-quinoxalyloxy)phenoxy]propionic acid (hereinafter referred to as compound (III)), which comprises reacting 4-(6-chloro-2-quinoxalyloxy)phenol (hereinafter referred to as compound (I)) or its alkali metal salt with L-2-chloropropionic acid (hereinafter referred to as compound (II)) or its alkali metal salt in an aromatic hydrocarbon solvent in the presence of an aprotic polar solvent and, if necessary, an alkali metal hydroxide, if necessary while carrying out azeotropic dehydration, to obtain an alkali metal salt of D(+)-2-[4-(6-chloro-2-quinoxalyloxy)phenoxy]propionic acid, and treating it with an acid.
By the process of the present invention, compound (III) can be produced at a high conversion in good yield without deterioration of the optical purity.
Fukuda Kenzo
Hatanaka Masataka
Ishii Kenichi
Makabe Takahiro
Nissan Chemical Industries Ltd.
Patel Sudhaker B.
Shah Mukund J.
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