FR2784986A1 - Preparation of indanone and thioindanone phytosanitary agents by cyclizing substituted aromatic compound in fluorinated organic sulfonic acid - Google Patents

Abstract

The preparation of indanones and thioindanones (III) comprises cyclizing an aromatic compound (I) substituted by a chain having a carbonyl or thiocarbonyl group and a reactive functional group, the cyclization being effected in the presence of a fluorinated organic sulfonic acid. An Independent claim is also included for the preparation of (I) by acylating an aromatic compound (IV) with an acylating agent (V) having a carbonyl or thiocarbonyl group. the acylated product is cyclized in the presence of an organic fluorinated sulfonic acid.

Description

PROCESS FOR THE PREPARATION OF AN NDANONE COMPOUND
OR THIOINDANONE.

 The subject of the present invention is a new process for the preparation of an indanone or thioindanone type compound by cyclization of an aromatic compound carrying a side chain comprising at least one carbonyl or thiocarbonyl group and one reactive functional group.

 The invention relates more particularly to the preparation of indanone from an alkylphenyl ketone halide and more particularly to chioroindanone from 3,4'-dichloropropiophenone.

The 5-chloroindanone which corresponds to the following formula is used in the phytosanitary field:

 It is obtained according to a process described in PCT / US / 96/20151 published under n 96/20151 which consists in bringing the 3,4'dichloropropiophenone into contact with a catalyst which can be sulfuric acid or a solid catalyst.

 When the solid catalyst is used, the reaction takes place at high temperature between 200 and 425 C.

 The reaction, carried out in the presence of sulfuric acid, takes place between 90 and 150 ° C. and in an inert organic solvent.

 In this case, the reaction yield is of the order of%.

 The objective of the present invention is to provide another preparation process in the liquid phase making it possible to obtain 5-chloroindanone with a very good reaction yield.

 It has now been found, and this is what constitutes the subject of the present invention, a process for the preparation of an indanone or thioindanone type compound from an aromatic compound carrying a side chain comprising at least one group. carbonyl or thiocarbonyl and a reactive functional group characterized in that it consists in carrying out the cyclization of the latter, in the presence of an effective amount of a sulfonic and fluorinated organic acid.

 In the preferred embodiment of the invention, which consists in using as starting aromatic compound, 3,4'dichloropropiophenone, it was unexpectedly found that the cyclization reaction was carried out with an excellent reaction yield as soon as the reaction was carried out in the presence of a sulfonic and fluorinated organic acid and more preferably trifluoromethanesulfonic acid commonly called "triflic acid".

The starting reagent of the process of the invention is an aromatic compound, preferably benzene, which carries a side chain which has 3 characteristics:
-a number of carbon atoms of 3 chained linearly in order to
form a ring with 5 carbon atoms by involving the 2 atoms
of benzene ring carbon,
a carbonyl group CO or CS in position a relative to the atom of
carbon of the benzene cycle to which the chain is connected,
-a reactive functional group.

 According to a preferred variant of the invention, the benzene ring carries at least one substituent which can be a halogen atom, a pseudohalogen group or an electron donor group.

dans ladite formule (I) :
-R représente un atome d'hydrogène, un atome d'halogène, un groupe
pseudohalogène ou un groupe électro-donneur,
-te représente un groupe fonctionnel réactif,
-Y symbolise un atome d'oxygène ou de soufre,
-n est un nombre égal à 0,1,2,3 ou 4, de préférence, égal à 1.Thus, the starting reagent can be symbolized by the form:

in said formula (I):
-R represents a hydrogen atom, a halogen atom, a group
pseudohalogen or an electron donor group,
-e represents a reactive functional group,
-Y symbolizes an oxygen or sulfur atom,
-n is a number equal to 0,1,2,3 or 4, preferably equal to 1.

 More precisely, one starts with an aromatic compound, preferably a benzene ring carrying a side chain comprising a carbonyl group CO or thiocarbonyl CS in position a relative to the carbon atom of the benzene ring which carries it and whose l Another characteristic is to have a number of carbon in the linear chain sufficient to form the cycle in C5, during cyclization.

 Thus, the side chain is a linear chain comprising 3 carbon atoms.

 Another characteristic of the side chain is to include a functional group capable of reacting in order to form the cycle.

 A first variant which is preferred consists in choosing as reactive group a halogen atom which is preferably a chlorine atom, which is located on the carbon atom in position | compared to the CO or CS group.

 Another variant consists in replacing the halogen atom with a hydroxyl group.

 Finally, another variant consists in using, as reactive functional group, a double bond located in position a, ss with respect to the group CO or CS.

 Indeed, and without limiting the invention to this interpretation, there is reason to believe that cyclization using a benzene compound carrying a carbonylated or thiocarbonylated side chain and carrying a halogen atom or d 'a hydroxyl group, passes intermediate by a dehydrohalogenation or dehydration step thus leading to the formation of a double bond and to the obtaining of a side chain compound of the same type as the third variant.

-un groupe

-un groupe

Thus in formula (I), the functional group can:
-a group

-a group

-a group

 In these different functional groups, RI, R2, R3, R4, identical or different, represent a hydrogen atom or an alkyl group which may be linear or branched and which generally comprises from 1 to 6 carbon atoms, preferably from 1 to 4 carbon atoms. R1, R2, R3, R4, which may be identical or different, preferably represent a hydrogen atom or a methyl or ethyl group.

 In the functional groups of formula (la) or (lob), preference is given to those which have at least one hydrogen atom having a of the carbon atom carrying X or OH. Thus, at least one of the groups RI and R3 is a hydrogen atom.

 The starting substrates capable of being used in the process of the invention can be compounds corresponding to formula (I) in which the benzene nucleus carries one or more substituents which can be a halogen atom, a group pseudohalogen or an electron donor group.

The group R may represent a halogen atom, preferably a chlorine or bromine atom; a pseudohalogen group and in particular a trifluoromethoxy, trifluorothiomethoxy, pentafluoroethoxy, pentafluorothioethoxy group,
The group R can also be an electron donor group.

In the present text, the term "electro-donor group" means a group as defined by HC BROWN in the work of Jerry MARCH-Advanced
Organic Chemistry, 4th edition, John Wiley and Sons, 1992, chapter 9, pp.

273-292.

As more specific examples of R groups, one can mention among others:
a hydroxyl group,
a linear or branched alkyl group having from 1 to 6 carbon atoms,
preferably from 1 to 4 carbon atoms, such as methyl, ethyl,
propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl,
an alkoxy group having from 1 to 6 carbon atoms, preferably from 1
with 4 carbon atoms,
an alkylamide group having from 1 to 6 carbon atoms, preferably 1
to 4 carbon atoms.

The preferred substrates of the process of the invention correspond to formula (I) in which R:
-a chlorine atom,
a hydroxyl group,
-a methyl or ethyl group,
-a methoxy or ethoxy group,
an acetamide group.

 Among the compounds corresponding to formula (I), the raw material of choice used in the process of the invention is 3,4 'dichloropropiophenone.

 In accordance with the process of the invention, the aromatic compound corresponding to formula (I) is cyclized in the presence of a sulfonic and fluorinated organic acid.

The acids preferably chosen in the process of the invention are organic sulfonic and perfluorinated acids, and more particularly the acids of the perfluoroalkyl- or perfluorophenylsulfonic type which can be symbolized by the following formula (11):
Rf-SO3H (II) in said formula Rf represents a perfluoroalkyl group having from 1 to 12 carbon atoms and from 3 to 25 fluorine atoms or a perfluorophenyl radical.

 As examples of acids preferably used in the process of the invention, mention may be made between: - trifluoromethanesulfonic acid or triflic acid, - 1,1,1-trifluoroethanesulfonic acid, - perfluorooctanesulfonic acid, - perfluorononanesulfonic acid, -perfluorobenzenesulfonic acid.

 Among the above-mentioned compounds, triflic acid is preferred.

 According to the process of the invention, the cyclization of the starting substrate is carried out in the presence of a sulfonic and fluorinated organic acid.

 A first embodiment of the invention consists in carrying out the reaction in said acid which is then used in a variable amount ranging from stoichiometry to a large excess when it is used as reaction solvent.

 More specifically, the amount of acid expressed by the ratio between the number of moles of acid and the number of moles of starting substrate preferentially corresponding to formula (I) varies between 1 and 30 and is preferably between 5 and 25.

 Another embodiment of the invention consists in using said acid deposited on a solid support.

 In this case, use is made of a support which is inert under the reaction conditions. As preferred examples of supports, mention may in particular be made of silica.

 It is also possible according to the process of the invention to add an organic solvent which is compatible with the sulfonic and fluorinated organic acid used and which is inert under the reaction conditions.

 Advantageously, an aprotic organic solvent is used.

 As more specific examples, there may be mentioned aliphatic, cycloaliphatic, aromatic, halogenated or not, such as, for example, n-pentane, hexane, heptane, octane, cyclohexane, 1,2dichloroethane, trifluoromethylbenzene.

 The amount of solvent used can be variable. One can for example, put an equivolumic quantity compared to the sulfonic and fluorinated organic acid.

 The cyclization reaction of the starting substrate takes place at a temperature which is advantageously between 50 C and 120 C, preferably between 80 C and 1 00 C.

 From a practical point of view, the reaction is simple to carry out.

 The substrate, the acid and optionally the organic solvent are charged and the mixture is heated to the desired temperature. The substrate can also be added gradually into the medium comprising the acid and optionally the solvent.

dans ladite formule (III), R, Ri, R2, R3, R4, Y et n ont la signification donnée précédemment.At the end of the reaction, the cyclized product is obtained which preferably corresponds to the following formula (fold):

in said formula (III), R, Ri, R2, R3, R4, Y and n have the meaning given above.

 The indanone or thioindanone compound is recovered according to the conventional techniques used, in particular by extraction in an appropriate solvent.

 One can for example add 1,2-dichloroethane and effect the hydrolysis of the reaction medium using a basic solution, preferably an aqueous solution of sodium or potassium hydroxide.

 The sulfonic and fluorinated organic acid is in salified form in the aqueous phase.

 After separation of the aqueous and organic phases, the cyclized product is recovered from the organic phase.

dans ladite formule (IV), R et n ont la signification donnée précédemment.The starting substrates involved in the process of the invention and which preferentially correspond to formula (1) are known products and described in the literature. They are obtained according to an acylation reaction of an optionally substituted aromatic compound corresponding to the following formula (IV):

in said formula (IV), R and n have the meaning given above.

 According to a particularly advantageous embodiment of the invention, it has been found that the acylation reaction of the aromatic compound can be carried out with the same sulfonic and fluorinated organic acid used in the cyclization reaction of the compound preferably corresponding to the formula ( 1).

 Another object of the invention is therefore the process which links the acylation reaction of the aromatic compound and the cyclization reaction.

 According to the invention, the aromatic compound and an acylation reagent which reacts with the CO or CS group and the reactive functional group are reacted.

 As aromatic compounds corresponding to formula (IV) preferably used, mention may be made of monochlorobenzene.

 As regards the acylation reagent, it may be of a different nature. It can be a carboxylic acid or derivative, halide, ester or anhydride.

dans ladite formule (V) : -Y symbolise un atome d'oxygène ou de soufre, -te représente un groupe fonctionnel réactif ayant la signification donnée précédemment, -Z représente :
. un atome d'halogène, de préférence un atome de chlore ou de brome,
. un groupe-O-C 0- dans lequel te représente un groupe fonctionnel
réactif tel que précédemment décrit,
. un groupe-O-R'dans lequel R'représente un groupe alkyle ayant de 1
à 6 atomes de carbone, de préférence, de 1 à 4 atomes de carbone,
Les réactifs d'acylation choisis préférentiellement répondent à la formule (V) dans laquelle : -Y représente l'oxygène, -2 représente un groupe fonctionnel réactif de formule (la) tel que précédemment décrit, -Z représente :
. un atome de chlore,
. un groupe-O-C O-te dans lequel le représente un groupe fonctionnel
réactif de formule (la) tel que précédemment décrit,
. un groupe-O-R'dans lequel R'est un groupe méthyle ou éthyle.It more specifically responds to formula (V):

in said formula (V): -Y symbolizes an oxygen or sulfur atom, -te represents a reactive functional group having the meaning given above, -Z represents:
. a halogen atom, preferably a chlorine or bromine atom,
. a group -OC 0- in which a functional group represents you
reagent as previously described,
. a group-O-R ′ in which R ′ represents an alkyl group having from 1
with 6 carbon atoms, preferably from 1 to 4 carbon atoms,
The acylation reagents preferably chosen correspond to formula (V) in which: -Y represents oxygen, -2 represents a reactive functional group of formula (la) as previously described, -Z represents:
. a chlorine atom,
. an OC-O-te group in which the represents a functional group
reagent of formula (la) as previously described,
. a group-O-R ′ in which R ′ is a methyl or ethyl group.

 Among the acylation reagents, use is preferably made of acylation reagents in the halide form.

 As examples of acylation reagents preferably used in the process of the invention, mention may be made of: - 3-chloropropionyl chloride, - acryloyl chloride, - 2-chloropropionyl chloride, - ester methyl 3-chloropropionic acid, -methyl ester of acrylic acid, -methyl ester of 2-chloropropionic acid, -3-chloropropionic acid anhydride, -alcohol acrylic acid, 2-chloropropionic acid anhydride.

 Among these reagents, more particularly 3chloropropionyl chloride is chosen.

 According to the invention, the acylation reaction is carried out in the presence of the sulfonic and fluorinated organic acid described above for the cyclization reaction.

 Advantageously, triflic acid is used.

 The acid is introduced in the same quantities as mentioned in the cyclization step, at the start of the reaction.

 As regards the amount of acylation reagent, it is most often close to stoichiometry. Thus, the ratio between the number of moles of acylation reagent and the number of moles of aromatic compound can range from 1 to 3, and is preferably between 1 and 2.

 According to a preferred embodiment of the process of the invention, the aromatic compound, the acylation reagent and the sulfonic and fluorinated organic acid are mixed, then the temperature of the mixture is brought to the temperature at which the reaction is carried out. .

 The temperature at which the acylation reaction is carried out is chosen so that the cyclization reaction is linked.

 It is therefore chosen in the same range and more particularly between 50 ° C. and 120 ° C., preferably between 80 ° C. and 100 ° C.

 Generally, the reaction is carried out at atmospheric pressure, but lower or higher pressures may also be suitable. One works under autogenous pressure when the reaction temperature is higher than the boiling point of the reactants and / or of the products.

 According to a preferred variant of the process of the invention, the process of the invention is carried out under a controlled atmosphere of inert gases. One can establish an atmosphere of rare gases, preferably argon, but it is more economical to use nitrogen.

 The reaction time is short of the order of 30 min to 2 hours.

 Thus, according to this embodiment of the invention, the cyclized product is obtained directly from the aromatic compound preferably corresponding to formula (IV).

 The cyclized product is recovered in a conventional manner and one can refer to the preceding description.

 The process of the invention is particularly suitable for the preparation of 5-chloroindanone from monochlorobenzene.

 The transformation of the intermediate compound, namely 3,4'dichloropropiophenone into 5-chloroindanone is almost quantitative.

 Examples of the invention are given below. These examples are given by way of illustration and without limitation.

Example 1
In this example, the cyclization of 3,4'dichloropropiophenone in triflic acid is carried out.

 In a 100 ml reactor, stirred by a magnetic stirrer, equipped with a dropping funnel, a thermometer, a reflux condenser and maintained under a nitrogen atmosphere, are charged: -0.41 g (2 mmol) of 3,4'-dichloropropiophenone, and 5 ml (8.45 g; 56 mmol) of triflic acid.

 The mixing is carried out at room temperature (20 ° C.) and then heated to 90 ° C. for 3 hours.

 After cooling to room temperature, the reaction medium is hydrolyzed by adding 50 ml of a water / ice mixture.

 50 ml of 1,2-dichloroethane are then added.

 The aqueous phase is neutralized to pH 5 using an aqueous solution of potassium hydroxide at 20% by weight.

 After decantation, the organic phase is washed with water (2 times 30 ml).

 The 1,2-dichloroethane is removed under reduced pressure (50 mm of mercury) and 325 mg of 5-chloroindanone is obtained.

 The reaction yield is%.

Example 2
In this example, the cyclization of 3,4'dichloropropiophenone in triflic acid and 1,2-dichloroethane is carried out.

 Example 1 is reproduced with the difference that it is: -0.44 g (2.15 mmol) of 3,4'-dichloropropiophenone, -5 mi (8.45 g; 56 mmol) of triflic acid, - and 5 ml of 1,2-dichloroethane.

 The mixture is heated to 80 ° C. for 3 hours.

 350 mg of 5-chloroindanone is obtained, which corresponds to a yield of 98%.

Free 3
In this example, the preparation of 5-chloroindanone from monochlorobenzene is described.

 In an apparatus as described in Example 1, there are: -0.25 g (2.21 mmol) of monochlorobenzene, -0.54 g (4.15 mmol) of 3-chloropropionyl chloride, -and 5 ml (56.3 mmol) triflic acid.

 The mixing is carried out at room temperature (20 C) and then heated to 120 C for 1 hour.

 After cooling to room temperature, the reaction is hydrolyzed by adding 50 ml of a water / ice mixture.

 Then added then 50 ml of 1,2-dichiorethane.

 The aqueous phase is neutralized to pH 5 using an aqueous solution of potassium hydroxide at 20% by weight.

 After decantation, the organic phase is washed with water (2 times 30 ml).

 The 1,2-dichloroethane is removed under reduced pressure (50 mm of mercury) and 0.165 g of 5-chloroindanone is obtained.

 The reaction yield is 45%.

Claims (28)

CLAIMS 1-Process for preparing a compound of indanone or thioindanone type from an aromatic compound carrying a side chain comprising at least one carbonyl or thiocarbonyl group and a reactive functional group characterized in that it consists in cyclize the latter, in the presence of an effective amount of a sulfonic and fluorinated organic acid. 2-A method according to claim 1 characterized in that the aromatic compound preferably benzene carries a side chain whose number of carbon atoms chained linearly is 3 to form a ring with 5 carbon atoms involving the 2 carbon atoms of the benzene ring; which carries a carbonyl group CO or CS in position a with respect to the carbon atom of the benzene ring to which the chain is: side chain which also carries a reactive functional group. 3-Method according to one of claims 1 and 2 characterized in that the aromatic compound carrying a side chain comprising at least one carbonyl or thiocarbonyl group and a reactive functional group corresponds to the general formula (I):

 in said formula (  -R represents a hydrogen atom, a halogen atom, a group  pseudohalogen or an electron donor group,  -e represents a reactive functional group,  -Y symbolizes an oxygen or sulfur atom,  -n is a number equal to 0, 1, 2,3 or 4, preferably equal to 1. 4-Process according to one of claims 2 and 3 characterized in that the aromatic compound carrying a side chain comprising at least one carbonyl or thiocarbonyl group and a reactive functional group corresponds to the general formula (I) in which the functional group 2 corresponds to one of the formulas:  -a group

 -a group

 -a group

 in said formulas (la) to (Ic), Ri, R2, R3, R4 identical or different represent a hydrogen atom or an alkyl group, linear or branched, comprising from 1 to 6 carbon atoms, preferably from 1 to 4 carbon atoms. 5-A method according to claim 4 characterized in that the functional group corresponds to one of the formulas (la) to (1c) in which R1, R2, R3, R4 identical or different, represent a hydrogen atom or a methyl or ethyl group. 6-A method according to claim 4 characterized in that the functional group? corresponds to one of the formulas (la) and (lob) in which at least one of the groups R1 and R3 is a hydrogen atom. 7-Method according to one of claims 2 and 3 characterized in that the aromatic compound carrying a side chain comprising at least one carbonyl or thiocarbonyl group and a reactive functional group corresponds to the general formula (I) in which the group R represents:  a halogen atom, preferably a chlorine or bromine atom,  a pseudohalogen group, preferably a trifluoromethoxy group,  trifluorothiomethoxy, pentafluoroethoxy, pentafluorothioethoxy,  a hydroxyl group,  a linear or branched alkyl group having from 1 to 6 carbon atoms,  preferably from 1 to 4 carbon atoms, such as methyl, ethyl,  propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl,  an alkoxy group having from 1 to 6 carbon atoms, preferably from 1  with 4 carbon atoms,  an alkylamide group having from 1 to 6 carbon atoms, preferably 1  to 4 carbon atoms. 8-A method according to claim 7 characterized in that the group R represents:  -a chlorine atom,  a hydroxyl group,  -a methyl or ethyl group,  -a methoxy or ethoxy group,  an acetamide group. 9-A method according to claim 1 characterized in that the compound of formula (I) is 3,4'-dichloropropiophenone. 10-Method according to one of claims 1 to 9 characterized in that the organic sulfonic and fluorinated acid is an organic sulfonic and perfluorinated acid, preferably an acid of the perfluoroalkyl- or perfluorophenylsulfonic type corresponding to the following formula (it ): Rf-SO3H (li) in said formula Rf represents a perfluoroalkyl group having from 1 to 12 carbon atoms and from 3 to 25 fluorine atoms or a perfluorophenyl radical. 11-A method according to claim 10 characterized in that the organic sulfonic and fluorinated acid is trifluoromethanesulfonic acid. 12-A method according to one of claims 10 and 11 characterized in that the sulfonic and fluorinated organic acid is deposited on a support, preferably silica or used as reaction solvent. 13-Method according to one of claims 10 to 12 characterized in that the amount of sulfonic and fluorinated organic acid expressed by the ratio between the number of moles of acid and the number of moles of starting substrate varies between 1 and 30 and is preferably between 5 and 25. 14-Method according to one of claims 1 to 13 characterized in that one adds an aprotic organic solvent, preferably, an aliphatic, cycloaliphatic, aromatic, halogenated or not. 15-Method according to one of claims 1 to 14 characterized in that the cyclization reaction of the starting substrate takes place at a temperature between 50 C and 120 C, preferably between 80 C and 100 C. 16-Method according to one of claims 1 to 15 characterized in that the substrate is loaded, the acid and optionally the organic solvent, which is heated to the desired temperature and that the product is recovered cyclized. 17-A method according to claim 16 characterized in that the cyclized product corresponds to the following formula (111):

 in said formula (III), R, R1, R2, R3, R4, Y and n have the meaning given in one of claims 3 to 8. 18-A method according to claim 17 characterized in that the compound of formula (III) is 5-chloroindanone. 19-Process for the preparation of an indanone or thioindanone type compound from an optionally substituted aromatic compound and an acylation reagent providing the carbonyl or thiocarbonyl group and the reactive functional group characterized by the fact that it consists carrying out the acylation reaction and the cyclization reaction of the acylated product obtained, in the presence of an effective amount of a sulfonic and fluorinated organic acid. 20-A method according to claim 19 characterized in that the aromatic compound corresponds to the following formula (IV):

 in said formula (IV), R and n have the meaning given in one of claims 3,7 and 8. 21-A method according to claim 20 characterized in that the aromatic compound of formula (! V) is monochlorobenzene. 22-A method according to claim 19 characterized in that the acylation reagent corresponds to formula (V):

 in said formula (V): -Y symbolizes an oxygen or sulfur atom, - represents a reactive functional group having the meaning given in one of claims 4 to 6, -Z represents:  . a halogen atom, preferably a chlorine or bromine atom,  . a group-O-C O-2 in which Ge represents a functional group  reagent as described in one of claims 4 to 6,  . a group-O-R ′ in which R ′ represents an alkyl group having from 1  with 6 carbon atoms, preferably from 1 to 4 carbon atoms, 23-A method according to claim 22 characterized in that the acylation reagent corresponds to formula (V) in which: -Y represents oxygen , -te represents a reactive functional group of formula (la) described in one of claims 4 to 6, -Z represents:  . a chlorine atom,  . a group-O-C O-te in which l2 represents a functional group  reagent of formula (la) described in one of claims 4 to 6,  . a group-O-R ′ in which R ′ is a methyl or ethyl group. 24-Method according to one of claims 22 and 23 characterized in that the acylation reagent used is chosen: -3-chloropropionyl chloride, -acryloyl chloride, -2-chloropropionyl chloride , -methyl ester of 3-chloropropionic acid, -methyl ester of acrylic acid, -methyl ester of 2-chloropropionic acid, -3-chloropropionic acid anhydride, - acrylic acid anhydride, - 2-chloropropionic acid anhydride. 25-A method according to claim 24 characterized in that the acylation reagent is 3-chloropropionyl chloride. 26-A method according to one of claims 19 to 25 characterized in that the amount of acylation reagent is such that the ratio between the number of moles of acylation reagent and the number of moles aromatic compound varies between 1 and 3, and preferably between 1 and 2. 27-A method according to one of claims 19 to 26 characterized in that the sulfonic and fluorinated organic acid is trifluromethylsulfonic acid. 28-A method according to claim 27 characterized in that the amount of acid introduced is as mentioned in claim 13. 29-Method according to one of claims 19 to 28 characterized in that one mixes the aromatic compound, the acylation reagent and the sulfonic and fluorinated organic acid and then brings the temperature of the mixture to the temperature to which the reactions are conducted. 30-A method according to one of claims 19 to 29 characterized in that the acylation reaction takes place at the same temperature as the cyclization reaction. 31-Method according to one of claims 19 to 30 characterized in that the cyclized product is obtained directly from the aromatic compound and more preferably 5-chloroindanone from monochlorobenzene.