Title of Invention

A PROCESS FOR THE PREPARATION OF CYCLOPENTADIENYL DERIVATIVE

Abstract

This invention relates to a process for preparing cyclopentadienyl derivatives of the fonnula Ib: It comprises the steps of condensing a ketone with an ester of succinic acid to produce a-(a'-cycloalkenyl)-p-hydroxycarbonyl alkyl propionate, subjecting the same to intianiolecular condensation followed by hydrolysis and decarboxylation. The a,p-unsaturated condensed ring obtained thereby is reacted with an alkyl/aralkyl derivative of an alkali metal to give the compounds of formula lb.

Full Text

CYCLOPENTADIENYL DERIVATIVES AND PROCESS FOR THEIR PREPARATION The present invention relates to new cyciopenradienyl derivatives and the process for their preparation. It is known that the more useful soluble catalysts for the homo- and co-polymerisation of a-olefins consist of zirconium or titanium complexes bearing ligands of bis-indenyl, bis-fluorenyl type, or mixed fluorenyl cyclopentadienyl type (P.C. Mchring, N.J. Coville, J. Organomet. Chem. 479, 1, 1994). It is also known zhaz the corresponding tetrahydrcincene derivacives, beside having a high activity, are more effective in the incorporation of CO- and ter-mcnomers and are, therefore, among the preferred catalysts. The indene or fluorene derivatives are easily avallable, but the corresponding tertrahydroindenyl derivatives are obtained by direct hydrogenation of the zirconium complex, as it is difficult to chemcselectively hydrogenate the starting ligands. The hydrogenation process of the complex shows, notwithstanding, somte inccveniences. In fact, as is reported by some experts (see E. Samuel, Bull. Soc Chim. Fr. , 3548, 1966 and S, Collins et al. in Organometallic Chem. , 342, 21, 1988) , in effecting said hydrogenation difficulties are found due to low yields and/or drastic conditions. New cyclopentadienyl derivatives have, now, been found, which overcome the above-mentioned disadvantages, because of their structure, they do not need the above-mentioned hydrogenation step of the complex with the zirconium. In accordance with this, the present invention relates to cyclopentadienyl derivatives having general formula (I) wherein: R/ Ri/ R2/ R^/ equivalent to or different from one another, are selected from: - H, - alkyl radicals having a number of carbon acorns from 1 to 5, - cycloalkyl radicals having a number of carbon atoms from 5 to 8, - aryl and alkylaryl radicals having a number of carbon atoms from 6 to 8, - aralkyl radicals having a number of carbon atoms from 7 to 9; n is an integer from 2 to 18; with the proviso that the number of R different from H does not exceed 2; with the exclusion of the compound having n=3, R=Ri=R2=R4=H. Typical examples of alkyl radicals from CI to C5 are methyl, ethyl, n-propyl, iso-propyl, n-butyl, isc-butyl, ter-butyl, n-pentyl, i so-pent yl, nec*- oentvl. •■ ^ Typical examioles of cycloalkyl radicals having a number of carbon atoms from 5 to 8 are cyclopentyl, cyclohexyl, methyl cyclopentyl, methyl cyclohexyl. Typical examples of aryl and alkylaryl radicals having a number of carbon atoms from 6 to 8 are phenyl, methyl phenyl, ethyl phenyl, dimethyl phenyl. Typical examples of aralkyl radicals having a numiber of carbon atoms from 7 to 9 are benzyl. methyl benzyl, ethyl benzyl, propyl benzyl. In a preferred form of embodiment, R, R1, R2, and R4 are selected from H and alkyl radicals from CI to C3. In an even more preferred form of emJDodiment, n is selected from 3, 5, 6, 10, R=R2=R1=H, R4 is selected from H and alkyl radicals from CI to C3. Typical examples of compounds having general formula (I) are; - If 4, 5, 6, If 8-hexahydroazulene (compound la in scheme 1, where R=R1=R2=H, n=5) ; 4, 5, 6, If 8, 9-hexahydro-2H- cyclopentacyclooctene (ccm;pcund la in scheme 1, where R=R1=R2= H, n=6; ; - 4, 5, 6, 1, 8, 9, IC, 11, 12, 13-decahydro-2H- cyclopentacyclododecene (compound la in scheme 1, where R=R1=R2=H, n=lG); - l-methyl-4, 5, 6, 7, 8, 9, 10, 11, 12, 13- decahydro-2H-cyclop€ntacyclodcdecene (compound lb in scheme 1, where R=R1=R2=H, R4=CK3, n=10) . The compounds having general formula (I) are useful as ligands in the preparation of the complexes with transition metals. Zirconium in particular, typical catalyst components in the (co)polymeR1sation of a-olefins. A process for the preparation of chemical compounds having general formula (I) constitutes a further object of the present invention. This process, schematically represented in scheme 1, where the compounds having general formula (I) are subdivided into (la) and (lb), compounds, whether R4 is equivalent to or different from H, foresees some common steps and a different final step as a function of R4. The process of the present invention, simple and oR1ginal, is schematized m Scheme 1. In accordance with this, the present invention relates to a process for the preparation of the compounds having general formula (la), where n is an integer from 2 to 18, preferably n is selected from 3, 5. 6, 10, and R, R1 and R2 have the above-mentioned meaning, preferably R=R1=R2=H, which compR1ses the following steps: a) Stobbe type condensation between a ketone having general formula (II) (-CHR-)n+i C=0 with an ester of the succinic acid having general formula (III) R3OOC-CHR2-CHR—COOR3, where the groups R3, equivalent or different from one another, are selected from m.oncfunctional alkyl radicals C1-C5, preferably R3 is selected from CH3 and CcH^ to give the a-(a'-cyclo-alkenyl)-p-hydrcxycarbchyl-alkyl propionate having general formula (IV); b) intramolecular condensation of the compound (IV) obtained in step (a) to give the condensed R1ngs com.pound having general formula (V) ; c) hydrolysis and decarboxylation of the compound (V) obtained in szep (b) to give the a-P unsaturated condensed R1ngs ketone having general formula (VI); d) reduction of the a-p unsaturated condensed R1ngs ketone (VI) obtained in step (c) to give the condensed R1ngs conjugated diene having general formula (la), steps (b) and (c) also being able to be carR1ed out in inverted order as compared to the above-mentioned one, or in a single step, preferably in the sequence (a), (b), (c), (d). Step (a) of the present invention is a typical condensation between ketones and esters of the succinic acid, known as Stobbe reaction. This reaction (see H. House, Modern Synthetic Reactions, pages 663-666, Organic Reactions, Volume VI, pages 2-58) consists in the condensation of a carbonyl deR1vative with a diester of the succinic acid. In case the carbonyl deR1vative is a cyclcaikanone^ as in the abcve-mentoned case, the hemiester of the cyclo alkenyl substituted succinic acid, having general formula (IV) is formed. Step (a) is carR1ed out in the presence of strong bases, such as sodium methoxide, sodium hydR1de, tertiary alcohol alcoholates, preferably potassium terbutylate, a typical non-nucleophile strong base. As far as the other expeR1mental details of the Stobbe reaction are concerned, please refer to the above-mentioned references. Typical cyclic ketones having general formula (II) are cyclobutanone, cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, cyclododecanone, 2-, 3-, 4- methyl cyclohexanone, phenyl cyclohexanone, benzyl cyclohexanone, One of the advantages of the process of the present invention consists in the fact that many ketones having general formula (II) are commercially available products. The condensation of step (a) occurs with a diester of the succinic acid having general formula (III) , preferably with a diethyl or dimethl succinate, eventually monosubstituted or disubstituted- Step (b) of the process of the present invention consists in an intramolecular condensation, with the elimination of water, of the product having general formula (IV) obtained in step (a) to give the condensed R1ngs compound having general formula (V) . This step is carR1ed out in the presence of usual condensation agents, for instance, strong acids such as sulphuR1c acid, hydrofluoR1c acid, phosphoR1c acid, polyphosphoR1c acid, preferably in the presence of polyphosphoR1c acid. The above-mientioned acid can be used as comimercially available or prepared in situ by mixing phosphoR1c acid and If polyphosphoR1c acid is used, it is preferable to carry out step (b) at temperatures between 70 and 110°C. Alternatively, step (b) can be carR1ed out in the presence of ZnCl2 in acetic acid - acetic anhydR1de, as is descR1bed in the above-mentioned quotation from Organic Reactions, Step (c) consists in the hydrolysis of the ester group and in the subsequent decarboxylation of the compound having general formula (V) to give the a-? unsaturated condensed R1ngs ketone having general formula (VI). The reaction is preferably carR1ed out in an acid enviroR1ment and at such temperatures as to facilitate the elimination and the removal of CO2/ preferably in a mixture of acetic acid/hydrochicR1c acid at reflux temperature- The a-p unsaturated ketone (VI) formed in step (c) is then reduced (step d) to a cyclopentadienyl deR1vative having general formula (la) in the presence of reducing agents such as sodium or lithium boron hydR1de, sodium hydR1de, lithium hydR1de, lithium aluminium hydR1de, preferably with LiAlH4. According to another form of embodiment of the process of the present invention, step (c) , i. e. the hydrolysis to carboxylic acid and the subsequent decarboxylation, can be carR1ed out before the step of intramolecular condensation (b), or the two steps can be carR1ed out in a single step by selecting the most appropR1ate reaction conditions. The process of the present invention does not necessaR1ly require the isolation of the single reaction products at the end of the single steps. Beside the advantage to start from easily available cycloalkanones, the process foresees rather simple chemical steps and has a satisfactory global yield. The present invention also relates to a process for the preparation of the com.pounds having general formula (lb) , where n is an integer from 2 to 18, preferably selected from 3, 5, 6, 10, R, R;, R2, R4 have the above-mentioned meaning but with the proviso that R^ is different from H, preferably R=R1=R2=H, which comipR1ses the following steps; a) Stobbe type condensation between a ketone having general formula (11) {-CHR-)n^i C=0 with an ester of the succinic acid having general formula (III) R3OOC-CHR2-CKR1-COOR3, where the groups R3, equivalent or different from one another, are selected from monofunctional alkyl radicals Ci-Cs, preferably R3 is selected from CH3 and C2H5/ to give the a-(a'-cyclc-alkenyl)-p-hydroxycarbonyl-aikyl propionate having general formula (IV); b) intramolecular condensation of the compound (IV) obtained in step (a) to give the condensed R1ngs compound having general formula (V); c) hydrolysis and decarboxylation of the compound (V) obtained in step (b) to give the a-p unsaturated condensed R1ngs ketone having general formula (VI); d) reaction of the a^P unsaturated condensed R1ngs ketone (VI) obtained in step (c) with an alkyl, aralkyl, alkylaryl, cyclcalky 1 deR1vative of ar. a 1 kali metal ar,d subsequent: hydrolysaticn to give the condensed R1ngs conjugated diene having general formula (lb), steps (b) and (c) being also able to be carR1ed out in inverted order as compared to the above-mentioned one, or in a single step, preferably in the sequence (a), (b), (c), (d) . As far as steps (a) to (c) are concerned, they are carR1ed out under the same conditions as the above-mentioned ones for the synthesis of (la) compounds. Step (d) is carR1ed out by reacting the a-p unsaturated condensed R1ngs' ketone (VI) obtained in step (c) with an alkyl, aralkyl, alkylaryl, cycloalkyl deR1vative of an alkali metal, preferably lithium. The hydrocarbon deR1vative of lithium is a function of the type of R4 that one is willing to introduce in the compound having general formula (lb). So, for instance, in case one is willing to prepare an (lb) compound where R4 is equivalent to -CH3, one will use methyl lithium; in case one is willing to prepare an (lb) compound where R^ is equivalent to -C2H5, one will use ethyl lithium. Step (d) then foresees a subsequent hydrolysis srep, preferably carR1ed out in the presence of acid catalysis, ar.c then a dehydration step, preferably carR1ed out in the presence of acid catalysis, icc. The product (lb) thus obtained can be isolated according to usual techniques. Accordingly, the present invention provides a process for the preparation of c\ clopentadicnyl compounds having tlic general formula (lb); where n is an integer from 2 to 18, R, R1, R2, R4 have tlie above-mentioned meaning but witli llie proviso that Rj is different from H, which compR1ses the following steps: (a) Stobbe type condensation between a ketone having formula (II); where the groups Ru equivalent or ditTerent from one another, are selected from monofimctional alkyl radicals Cj-Cj, to give the a-(a'-cycloalkenyl)-p-hydroxycarbonyl-alkyl propionate having fonnula (IV); (b) intramolecular condensation of the compound (IV) obtained in step (a) to give the condensed R1ng compound having fonnula (v): (c) hydrolysis and decarbox\'lation of the compound (V) obtained in step (b) to gi\ e t!ie a,(3-unsaturated condensed R1ng ketone having formula (VI): (d) reaction of the a,p-unsaturated condensed R1ng ketone (VI) obtained in step (c) with an alkyl, aralkyl, alkylar>l. cycloalkyl deR1vative of an alkali metal and subsequent hydrol>*zation to give tlie conjugated condensed R1ng diene having formula (lb), steps (b) and (c) also being able to be carR1ed out in the inverted order as compared to llie above mentioned one, or in a single step. Tlie following examples are reported for a better illustration of the present invention. EX.AAiPLE 1 - S>irthesis of 2, 4, 5, 6, 7, 8-hexahydroazulene (compound of scheme 1 where R-R;=R2-H, n-5). io a solution of cycloheptanone, compound (II) where n=5, (56 grams corresponding to 0.5 moles) and of diethyl succinate, compound (III) where both R3S are equal to -C-H5, 110 giams (0.63 moles ) in 500 ml N,N dimethyl formamide (DMF), potassium terbutylate (75 grams, 0.67 moles) is slowly added (in about 1 hour), maintaining the temperature between 20 and 30 °C, At the end a yellow suspension is obtained which, after about one hour is dissolved again to give, then, a complete solidification of the reaction product. It is all poured in about 2 liters water, thus obtaining a limpid solution. The solution is extracted for some times with ethyl ether and the aqueous solution is then acidified to a pH of 2-3, by using dilute HCl. The aqueous solution thus acidized is then extracted with ether and the organic extract, after washing with water to neutrality and after drying, is evaporated, 118 grams (99% yield) a-(a'-cycloheptenyl)-p-hydroxycarbonyl-ethyl procicnare (ccm.pound IV) are obtained pure at the NMR analysis. The emiester (IV) is then added to a mixture consisting of 400 grams HaPO^ 85% and 650 grams P2O5, miaintaining the temperature between 90 and 92°C. Once the addition has ended, the temperature is maintained for further 4 hours, duR1ng which there is an abundant development of foami. The mixture is then hydrolized with water and extracted with diethyl ether. The ethereal extract is neutralized and dR1ed. After the evaporation of the solvent, 35 grams of raw residue (64% yield of product V)are obtained, which are poured into 100 ml AcOH, 100 ml water and 10 ml concentrated HCl and then maintained at reflux temperature for one night. The reaction mass is diluted with water and extracted with petroleum ether. After the neutralization, drying and evaporation of the solvent, 16 grams 3, 4, 5, 6, 7, 8-hexahydro-2H-azulen-1-one (64% yield of product VI) are obtained. 16 grams of product (VI) dissolved in 200 ml diethyl ether are added to a solution of 3.0 grams of LiAlH^ in 300 m.l diethyl ether, maintaining the temperature between 5 and 10°C- The reaction mixture is then hydrolized, the ethereal layer separated and the aqueous s::ep extracted, again with 200 ml diethyl ether. The ethereal extracts, (800 ml) after neutralisation and anhydR1fication are treated with 1.0 grams p-toluenesulphonic acid for 1.5 hours at room temperature. The organic phase is then neutralized with NaHC03 and evaporated. The residue obtained is puR1fied by chromatography on a silica gel column by eluting it with petroleum ether. 14 grams of 2, 4, 5, 6, 7, 8-hexahydroazulene, (compound la with n=5) are obtained with a yield of 98% from the product (VI) ar.d of 4 0% from the starting cycloheptanone, which has the following NMR spectrum: ^H-NMR (CDCI3, 5 ppm rel. TMS) : 5.96 (s, br, 2H) ; 2.84 (t, 2H, J=2Hz); 2.47 (m, 4H); 1.61 (m, 6H), EXAMPLE 2 - Synthesis of 4, 5, 6, 1, 8, 9-hexahydro-2H-cyclopentacyclooctene (compound la of scheme 1 where R=R1=R2=H, n=6) . A solution of 63 grams (0.5 moles) of cyclooctanone (II) and 110 grams (0.63) moles diethyl succinate is prepared. 75 grams (0.67 moles) Potassium terbutylate are added tc this solution in sm^all portions. After the addition, the m.ixture is left under stirR1ng for 4 hours. The orange mass is hydrolized with water and ice, one acidizes and one extracts with diethyl ether. 140 gramiS of a raw semi-solid containing two products in a ratio 84:16 are obtained upon evaporation. 70 grams of the raw ester thus prepared are added to the polyphosphoR1c acid (consisting of 300 grams 85% H3PO4 and 4 50 grams P2O5) • Exothermac reaction takes place and at 70°C the ester goes into a solution, the mass browns and the temperature goes up i-o 92°C. The reaction mass is stirred for about H hour. The temperature goes down to 80°C. The reaction mixture is pored into ice, is extractd with diethyl ether, neutralized with an aqueous solution of NaHCOa, anhydR1fied and the solvent evaporated. 35 grams brown oil are obtained. A mixture is prepared containing the 35 grams of the above-mentoned raw oil, 100 ml AcOH, 100 ml water and 10 ml concentrated HCl. This mixture is maintained at reflux temperature for 6 hours^ at the end of which is hydrolized and extractd with diethyl ether. Many pitches separate. The mixture is washed with NaOH (pitches dissolve) and water, anhydR1fied aR1d the solvent evaporated. 12 grams yellow oil are obtained. These 12 grams yellow oil (corresponding to product VI), dissolved in 100 ml diethy ether, are added to a solution of 3.0 grams LiAlH4 in 200 ml diethyl ether, miaintaining the temperature between 5 and IC'C. The reaction mixture is then hydrolized, the ethereal layer separated and the aqueous step extracted, still with 100 ml diethyl ether. The ether extracts (400 ml) , after neutralisation and anhydR1fication, are treated with 1.0 grams p-toluenesulphonic acid for 1.5 hours at room temperature. The organic phase is then neutralized with NaHC03 and evaporated. The residue obtained is puR1fied by chromatography on a silica gel column by eluting with petroleum ether. 7 grams of (la) product, pure at the NMR and GC analysis, are obtained. The yield, as compared to the starting cyclooctanone (II), is of 20%. The NMR spectrum of the 4, 5, 6, 7, 8, 9-hexahydro-2H-cyclopentacyclooctene thus obtained is the following; 'H-NMR (CDClj, 5 ppm rel. TMS) : 6.02 (t, 2H) ; 2.88 (bs, 2K); 2.50 (t, 4H) ; 1.70-1.40 (m, 8H) . EXAMPLE 3 - Synthesis of 4, 5, 6, 7, 8, 9, 10, 11, 12, 13-decahydro-2H-cyclopentacyclododecene (compound la of scheme 1 where R=R1=R2=H, n=10) . To a solution of 100 grams (0.549 moles) cyclododecanone (compound II, n=10) in 700 ml THE, 70 grams Potassium terbutylate are slowly added ; about \ hour) . At the end, a yellow suspension is obtained which is agitated for 1 hour. The whole is poured in about 2 liters water, thus obtaining a limpid solution. The aqueosus solution is washed for some times with diethyl ether and then acidicified to a pH of 2-3, by using diluted HCl. The aqueous solution is then extracted with ether and the organic extract, after washing with water to neutrality and after drying, is evaporated. 160 grams (94% yield) of a product having a low melting point (product IV in scheme 1 where n=10, R=R1=R2=H, R3=Et) are obtained. The ester thus obtained (120 grams, 0.387 moles) is poured in one hour into a flask, maintained at about 93-95°C, containing 2.5 Kg polyphosphoR1c acid having a P2O5 content of 84%. Once the addition has ended, the temperature is raised to 96-97 °C and the mixture left under starR1ng for 4 hours. The mixture is then hydrolized with water and extracted with diethyl ether. The ether extract is neutralized and dR1ed. After the evaporation of the solvent, 90 grams of a raw residue, pure at the GC analysis (product V in scheme 1, where n=10, R=R1=R2=H, R3=Et) are obtained. The solid is put into a solution consisting in 125 ml AcOH, 12 5 ml water and 10 ml concentrated KCl, and maintained under reflux temperature for 20 hours. The reaction mass is diluted with water and extracted with petroleum ether. After the neutralization, drying and evaporation of the solvent, the residue is distilled under vacuum and the fraction which passes at 125-130°C/0.2 mmHg is collected. 4 3 grams (51% yield) of product VI in scheme 1 having n=10, R=R1=R2=K, are obtained. 24 grams (0.11 moles) of the product thus obtained are dissolved in 200 ml diethyl ether and then added to a solution of 3.0 grams LiAlH^ in 300 ml diethyl ether, maintaining the temperature between 5 and 10°C. The reaction m^ixture is then hydrolized with some diluted KCl, the ethereal layer separated and the aqueous phase extracted still with 200 mJ diethyl ether. The ethereal extracts, (800 ml) after neutralisation and anhydR1fication are treated with 2.7 grams p-toluenesulphonic acid for 1.5 hours at room temperature, then at 30-35°C for 5-6 hours until the alcohol (TLC) has disappeared. The organic phase is then neutralized with NaHC03 and evaporated. The residue obtained is puR1fied by chromatography on a silica gel columin by eluting with petroleum ether. 21 grams (99% yield) ot a mixture consisu^ag m two products in a ratio of 81:19, of which the main product is 4, 5, 6, 7, 8, 9, 10, 11, 12, 13-decahydro-2H-cyclopentacyclododecene (compound la in scheme 1, n=lC, R=R1=R2=H) are obtained. EXAMPLE 4 - Synthesis of 1-methyl- 4, 5, 6, 7, 8, 9, 10, 11, 12, 13-decahydro-2H-cyclopentacyclododecene (compound lb in scheme 1, where R=R1=R2=H, R4=CH3, n=10). To a solution, in 100 ml diethyl ether, of 10 grams (0.045 moles) of the carbonylic deR1vative prepared in example 3 (product VI in scheme 1, n=10, R=R: = R2=H) , maintained at -7C°C, 30 ml of a solution 1,6 M of MeLi in diethyl ether are added. The miixture is left under stirR1ng for one night, then hydrclyzed. The ethereal phase is separated, 1 gram p-tcluenesulphonic acid is added and the mixture is lefi under stirR1ng for 2 hours. Tne mixwure is neutralized with a saturated solution of sodium bicarbonate, dR1ed on NasSO^ and the solvent is evaporated. The product is eluted on a silica gel column by using petroleum ether and by collecting the first fraction. 7 grams of a product consisting in two isomers in a ratio of 3:1 from the gaschromiatographic analysis are obtained. The main product of the above-mentioned mixture is consisting in l-methyl-4, 5, 6, 7, 8,9, 10, 11, 12, 13-decaliydro-2II-cyclopentacyclodedecene. This application has been divided out of Indian Patent application no. 146l.MAS/96 which relates to a process for prepaR1ng compounds of tlie formula Ka); WE CLALM: I. A process for the preparation of cvclopentadienyl compounds having the general formula (Ih): where n is an integer trom 2 to 18, R, Ri, R:, R4 have the above-mentioned meaning but \vith the proviso that R4 is different from H, which comprises the following steps: (a) Stobbe type condensation between a ketone having formula (II); with an ester of the succinic acid having fomula (III) COOR; ! CHR: 1 ! CHRi I COOR3 where the groups R3, equivalent or different from one another, are selected from monofimctional alkyl radicals Ci-C^, to give the a-(a'"Cycloalkenyl)-P-hydroxycarbonyl-alkyl propionate having fomiula (I\^: (b) intramolecular condensation of the compound (IV) obtained in step (a) to give the condensed ring compound having formula (v): (c) hydrolysis and decarboxylation of the compound (V) obtained in step (b) to give the a,f:i-un.saturated condeiLsed ring ketone having formula (VI): (d) reaction of tlie oup-unsaturated condensed ring ketone (VI) obtained in step (c) with an atkvL aralkyi, alkyianl, cycloalkyl derivative of an alkali metal and subsequent hydrolyzation to give the conjugated condensed rii^g diene having formula (lb), steps (b) and (c) also being able to be carried out in the inverted order as compared to the above mentioned one, or in a single step. 2. The process according to claim K wherein R? is selected from -CH3 and "C2H5. 3. The process according to claim 1, wherein R=R1-R2=H. 4. Tlie process according to claim 1, wlierein n is selected from 3, 5, 6, 10. 5. The process according to claim 1, wherein step (a) is carried out in the presence of Potassium terbutylate. 6. The process according to claim 1, wherein step (b) is carried out in the presence of polyphosphoric acid as h is or prepared in situ. 7. The process according to claim L wherein step (c) is carried out at acid pHs. 8. The process according to claim 1, wherein in step (d) the alkali metal is Lithium and tlie hydrolysis is carried out with acid catalysis. 9. The process according to claim 1, wherein the process is carried out in the following step sequence step (a), step (b), step (c), step (d). 10. A process for the preparation of compounds of the formula (lb) substantially as herein described.

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