Substituted cinnamic acids and cinnamic acid esters

Details Substituted cinnamic acids and cinnamic acid esters Substituted cinnamic acids and cinnamic acid esters

2001-02-13

2002-09-24

Rotman, Alan L. (Department: 1625)

Organic compounds -- part of the class 532-570 series

Organic compounds

Carboxylic acid esters

C560S055000, C562S104000, C562S105000, C562S493000

Reexamination Certificate

active

06455725

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to substituted cinnamic acids and cinnamic acid esters, to a process for their preparation and to their use for synthesizing insecticide precursors.
The synthesis of insecticides is of high importance. Important intermediates in this synthesis are the substituted indanonecarboxylic acid esters and their salts.
WO 95/29171, for example, discloses a process for preparing oxadiazines which are used in the field of crop protection for controlling arthropods. In the multistep preparation process, use is made, inter alia, of substituted indanonecarboxylic acid ester intermediates. The synthesis of the substituted indanonecarboxylic acid esters comprises a Friedel-Crafts reaction of para-substituted phenylacetyl halides with ethylene in the presence of a Lewis acid and an inert solvent with formation of a 2-tetralone of the formula A, where R
1
represents F. Cl or C
1
-C
3
-fluoroalkoxy,
the reaction of the compound A with peroxycarboxylic acids with formation of substituted arylpropionic acids of the formula B,
the esterification of the substituted arylpropionic acids of the formula B with C
1
-C
3
-alcohols in the presence of an acid catalyst with formation of the substituted arylpropionic acid esters of the formula C, where R″ represents C
1
-C
3
-alkyl,
and the reaction of the compounds C with a base with ring closure and formation of the substituted indanonecarboxylic acid ester of the formula D
This synthesis of the substituted indanonecarboxylic acid esters has the disadvantage that the addition of from 0.9 to 1.5 molar equivalents of a Lewis acid, such as, for example, aluminum trichloride, is required in the Friedel-Craft reaction for the reaction of the phenylacetyl halides with ethylene. As a consequence, large amounts of salts are produced during work-up of the reaction mixture, and thus corresponding volumes of contaminated waste water. Additionally, this synthesis requires the use of peroxycarboxylic acids, such as, for example, peroxyacetic acid, for cleaving the 2-tetralone. For this purpose, the peroxycarboxylic acids have to be employed in an amount of from 2.5 to 3.5 molar equivalents. If the reaction is carried out on an industrial scale, this causes safety risks. Therefore, the reaction temperature has to be exactly maintained and, furthermore, the addition of the peroxycarboxylic acid has to be controlled accurately to avoid an accumulation of excessive amounts of excess peroxycarboxylic acid in the reaction system.
It is furthermore known from J. Pharm. Sci. 67(1) 1978, 81, to prepare the chloro-substituted indanonecarboxylic acid ester 5-chloro-2-methoxycarbonyl-1-indanone starting from 3-chlorobenzaldehyde. Here, 3-chlorobenzaldehyde is initially reacted in pyridine with malonic acid to give 3-chlorocinnamic acid. Following hydrogenation of the ethylenic double bond and cyclization to the 5-chloro-1-indanone, the latter is then reacted with dimethyl carbonate in the presence of sodium hydride and benzene as solvent to give 5-chloro-2-methoxycarbonyl-1-indanone. This synthesis method has the disadvantage of the multistep mechanism which considerably increases the likelihood of the formation of various by-products, which is reflected in only a low yield of 48%. Additionally, the total reaction requires the repeated use of substances such as sodium hydride and benzene, which are expensive, problematic with respect to safety or hazardous to health.
Chemical Abstracts 97, 1982, 109843f discloses 5-bromo-2-carboxy-cinnamic acid which is obtained by oxidative cleavage of 6-bromo-2-naphthol and is then cyclized, reacted with PCl
5
and NH
3
to give the amide and subsequently, with ring enlargement, reacted in the presence of NaOCI to give 6-bromo-isoquinolin- 1-one.
Also known from Chemical Abstracts 82, 1975, 31200n and 79, 1973, 91891m, is the oxidative cleavage of 6-bromo-2-naphthol with formation of 5-bromo-2-carboxy-cinnamic acid, which leads, via a plurality of steps of amidation, Hoffmann rearrangement and cyclization, to the corresponding substituted indoles.
WO 97/43287 A1 discloses, in a general manner, substituted cinnamic acids and cinnamic acid chlorides which may be substituted on the phenyl ring by a radical R
1
and one or two further radicals R
2
, a large number of meanings being possible for these radicals. Also described is the reaction of the substituted cinnamic acids and cinnamic acid chlorides with other complex starting materials to give specific carboline derivatives which are used as cGMP-PDE inhibitors for cardiovascular indications.
WO 96/04241 A1 discloses, in the form of preparation 45, a cinnamic acid which is substituted in one m-position of the 2-carboxyvinyl radical by methyl carboxylate and in the other m-position by iodine. WO 96/04241 is focused on the preparation of specific, pharmaceutically active benzoylguanidine derivatives, in which the preparation 45 is also used.
EP-A-0 508 264 discloses a process for preparing broadly defined arylolefins which, in a general manner, also include substituted cinnamic acids and cinnamic acid esters. The arylolefins that can be prepared are used in very different areas, for example as optical brighteners, as precursors for optical brighteners, as intermediates for pharmaceutics or as UV absorbers.
DESCRIPTION OF THE INVENTION
Accordingly, it was the object of the present invention to provide intermediates which can be used to synthesize substituted indanonecarboxylic acid esters in a technically simple manner, which does not involve any safety risks.
This object is achieved by substituted cinnamic acids and cinnamic acid esters of the formula (I)
where X represents F, Cl or J and R
1
and R
2
are identical or different and represent hydrogen, an optionally substituted C
1
-C
10
-alkyl radical or an optionally substituted benzyl radical.
These substituted cinnamic acids or cinnamic acid esters are distinguished by the fact that, for the first time, they allow, in an unexpectedly simple two-step process, a low-cost synthesis of substituted indanonecarboxylic acid esters.
In the substituted cinnamic acids or cinnamic acid esters, X represents F, Cl J, preferably chlorine.
R
1
and R
2
are identical or different and represent hydrogen, an optionally substituted C
1
-C
10
-alkyl radical or an optionally substituted benzyl radical. Preferably, R
1
and R
2
independently of one another represent hydrogen, methyl, ethyl, propyl, i-propyl, n-butyl, i-butyl, tert butyl, n-pentyl, i-pentyl, n-hexyl, i-hexyl, n-heptyl, i-heptyl, n-octyl, i-octyl, n-nonyl, i-nonyl, n-decyl or i-decyl. In particular, R
1
and R
2
independently of one another represent hydrogen or methyl.
If the C
1
-C
10
-alkyl radical is substituted as radical R
1
or R
2
, these substituents can be halogen, hydroxyl or C
6
-C
12
-aryl radicals. The benzyl radical as radical R
1
or R
2
can be substituted by halogen, hydroxyl, C
1
-C
10
-alkyl or C
6
-C
12
-aryl radicals.
In the cinnamic acids or cinnamic acid esters of the formula (I), the substituent X is preferably in the 5-position to the acrylic acid or acrylic acid ester radical.
Preferred compounds of the formula (I) are methyl 4-chloro-2-(3-methoxy-3-oxo-1-propenyl)benzoate, 4-chloro-2-(3-methoxy-3-oxo-1 -propenyl)-benzoic acid, 4-fluoro-2-(3-methoxy-3-oxo-1-propenyl)benzoic acid, methyl 4-chloro-2-(3-hydroxy-3-oxo-1-propenyl)benzoate or 4-chloro-2-(3-hydroxy-3-oxo-1-propenyl)benzoic acid.
The substituted cinnamic acids or cinnamic acid esters of the formula (I) can be prepared by a variation of the Heck reaction (Process A).
The invention provides a process for preparing the substituted cinnamic acids and cinnamic acid esters of the formula (I) by reacting diazonium salts of the formula (II
0
with acrylic acid derivatives of the formula (III) in the presence of a palladium-containing catalyst, where X, R
1
and R
2
are as defined in formula (I) and A- represents halide, preferably chloride or bromide, sulfate, hydrogen sulfate, nitrate, phosphate, acetate or tetrafluoroborate, characterized in that th

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