PROCESS FOR THE PREPARATION OF FLUORINATED HETEROCYCLIC COMPOUNDS

Abstract: A method of fluorinating a heterocyclic organic compound comprises the step of reacting a heterocyclic compound with elemental fluorine in the presence of another halogen (e.g. I2). The reaction may be conducted in the presence of a base.

Description: PROCESS FOR THE PREPARATION OF FLUORINATED HETEROCYCLIC COMPOUNDS The present invention relates to the preparation of halogenated compounds, in particular, halogenated heterocyclic compounds More particularh . the invention relates to the fluoπnation of heterocyclic compounds The preparation of halogenated heterocycles has received a great deal of attention due to the many synthetic and industrial processes in which such substrates are ed. for example, in the pharmaceutical, plant protection and dye industries Few methods are available for the introduction of a fluorine atom at the 2- and/or 6-posιtιons of pyπdine Traditional!} . routes to 2-fluoropyπdιnes have been based on multi-step Balz- Schieman type decompositions of pyπdine diazonium tetrafluoroborate salts Halogen exchange processes involving the reaction of a fluoride ion source, such as SbF5. KF. HF. etc. with a chlorinated pyπdine at elevated temperatures have frequently been used to prepare fluoropyπdines The electrochemical fluoπnation of pyπdine in the presence of a source of fluoride ion gave 2-fluoropyπdιne in onh 22% yield With xenon difluoride. pyπdine gave a mixture of fluoropyπdines and. also, cesium fluorooxysulfate reacts with pyπdine at room temperature in ether to give 2-fluoropyridιne in 61 % yield The preparation of related fluoπne-containmg heterocycles such as 2-fiuoroquιnolιne be accomplished similar methodology . le halogen exchange processes, fluorodediazotisation. etc Preparations of 2-fluoropyπdιnes b direct reaction with elemental fluorine have been reported However, the reactions are kinetically competitive with side chain fluoπnation and. consequent . yields of 2-fluoropyπdιnes are low The reaction of elemental fluorine with quino ne results in predominant fluoπnation of the annulated aromatic ring and extensive fragmentation of the hetero-πng Surprising!} . it has now been found that heterocyclic compounds can be selective ] } fluoπnated b} elemental fluorine when another halogen is present in the reaction medium According to the present invention, there is provided a method of preparing a heterocvclic organic compound having at least one fluorine substituent in the heteroc}clιc ring, the method compπsing the step of reacting a heterocyclic compound with elemental fluorine in the presence of another halogen The other halogen ma} comprise chlorine, bromine or iodine or ma} comprise an interhalogen compound such as iodine monobromide or iodine monochloπde The heteroc clic compound which is fluormated b\ the method of the present invention ma} be a nitrogen-containing heteroc} chc compound The heterocyclic compound ma} include a fiv e- or sι\-membered ring which ma} contain optional substituents The ring ma} be attached or fused to another one or more rings which ma} or ma} not be heterocyclic The heterocyclic compound preferabh includes a six-membered aromatic nng containing one or more nitrogen atoms such as pyπdine or a related heterocycle such as pynmidine. pyπdazine or tπazme. or a related benzo-fused heterocycle such as quinohne. isoquinoline. quinoxahne or quinoazohne. or a bi-or poh -cyclic compound such as bipyridine The positions of the ring or rings of the heterocyclic compound fluormated b} the method according to the present invention which are not occupied b} heteroatoms ma} cany substituents Thus where the heterocycle is pyπdine it ma}' cam substituents at from one to five ring positions Where the heterocycle is a pynmidine it ma} carry substituents at from one to four ring positions Wnere the heterocycle is quinohne or isoquinoline it ma} earn substituents at from one to six ring positions Optional nng substituents which ma} themselves contain optional substituents ) ma} be independent!} selected from alky 1. alkoxv . halogen -CΛ -OH -NO : . -NH_. NHal Λ l. -N( ) 2 . -NHCOalk} !. -COOalkv l. -COOH l. -CONH : -CONH(alk} ] > -CONfalkv l), -COY -CY 1 ^ and SO : Y : wherein Y is -H. -F. -Cl. -Br. alky L -OH or -Oalky l Y ls -F or -Cl Y : is -F. -C l . -Br. -NH-.. -NHalkvl. or - (alkvl )-, SUBSTITUTE SHEET PULE 26 In each of these substituents alky 1 is preferabh C ,_ 4 -alk l. alkox} is preierabl} and halogen is preferabh -F or -Cl When the aromatic compound is pyπdine. it is preferabh unsubstituted. monosubstituted or disubstituted When pyπdine is monosubstituted. it is preferabh substituted in the 4-posιtιon When pyπdine is disubstituted. it is preferabh substituted in the 2- and 4-posιtιon Preferred substituents for the heterocyclic compound are selected from -OH. -CN. -NO : . NHCOCH;. -OCH-,. -COOCHv -COOH. -COCH,. -CH -F. -Cl. -Br. -CF-. and -CONH 2 and combinations thereof All hydrogens on carbon atoms bonded to the heteroatom ma} be substituted b} fluorine if the stoichiometr} of the expeπment is altered For instance, two fluorine atoms ma} be selectiveh introduced into heterocyc cs as. for instance, pyπdine gave 2.6-difluorop} πdine when two equivalents each of fluonne and. halogen were used B} a similar process, quinoxa ne gav e 2.3- difluoroquinoxaline and pynmidine gave difluoπnated pyπmidines In a preferred method according to the present invention, a base is added to the reaction medium The base ma} be an organic base such as tπethylamine or an inorganic base such as sodium fluoride It has been surprising]} found that this addition of a base to the reaction medium giv es a significant]} higher conversion of stamng heterocyclic to fluormated products in a given time Examples of fluoπnations which may be earned out by the method of the present inv ention ar- given in Figure 1 of the accompanying drawings The groups R, to Rj are independent!} selected from h} drogen and the various substituents for hydrogen specified above Figure 2 of the accompanying drawings gives examples of fluoπnations b} the method of tne present invention in which two fluorine atoms are introduced into the heterocycle Again the groups are R, to R 4 are independent!} selected from hvdrogen and the v arious substituents fo hydrogen specified above The ratio of halogen to the heterocyclic compound ma} be v aried within w ide limits although it is prefeπed that the molar ratio is in the range 0 2 to 8 0 1. especialh 1 0 to 1 4 1 (halogen or interhalogen heterocvclic compound) Examples of organic bases which ma} be used are tπethylamine. tributylamme and N- methylpipeπdine Examples of organic bases are sodium fluoride and potassium fluoride The ratio of base to the heterocyclic compound ma} be varied within wide limits although it is preferred that the molar ratio is in the range 0 2 to 8 0 1. especialh 1 0 to 1 4 1 (base heterocyclic compound) The method according to the present invention ma} be carried out b} passing fluorine gas into a liquid which contains the heterocyclic compound, halogen and. if used, base The reaction ma} be carried out in the vessel in which the liquid is present or alternatively, a flow -stream of the liquid may be contacted with the gaseous flow of fluoπne in countercurrent fashion The liquid may comprise a common men. organic solvent such as acetonitrile or a fluormated organic liquid such as a fluormated alkane (eg CF ; ClCFCl : ) a perfluoroalkane. perfluorodeca n. a fluormated ether, a perfluoπnated ether, or a partly fluormated alkane The process may be earned out at a temperature from -20°C to 80°C. preferabh at a temperature from -\ 0X to 30 L C and especially at a temperature from -5 C to 25°C The fluonne gas is preferabh diluted before use by mixing with an men gas such as nitrogen or helium The concentration of fluoπne is preferabh from 1% to 50% b} olume, more preferabh from 2% to 25% and especialh from 5% to 15% The ratio of fluorine to heterocyclic compound ma} be varied within wide limits although it is prefeπed that the molar ratio of fluorine to aromatic compound is from 0 5 1 to 6 1 and especialh from 1 1 to 4 1 L'se of a higher ratio of fluorine to heterocv clic compound ensures that more than one fluorine atomic can be selectiveiv introduced into the heterocyclic compound When fluoπnation is complete, the fluormated products mav be isolated purging the reaction mixture with nitrogen to remove an} residual fluoπne gas. followed b} dilution with excess water and neutralisation, followed b} extraction into a suitable solvent, followed by distillation The fluormated heterocyclic products may be separated b} fractional distillation, chromato graph} or b} crystallisation from a suitable solvent The method according to the present invention offers a simple, convenient route to the preparation of fluormated heterocycles directly from the parent heterocycle and elemental fluorine Thus, the preparation of chlorinated heterocycles for halogen excnange reactions or animated heterocycles for dediazotisation reactions is not necessary in the method of the present invention Thus, the present method offers a simple one-step procedure for the preparation of fluormated heterocycles The introduction of a base into the reaction mixture ensures rapid conversion of starting material to product and is. therefore, a particularly advantageous embodiment of the present invention The method according to the present invention is further illustrated with reference to the following examples F xample 1 Preparation of 2-fluoropvπdιne A solution containing pyπdine (9.5g. 120mmol) and iodine (30 Og. 1 18mmol ) in .Arklone (Trade Mark) (CFCh-CFC ) (150 ml ) was placed in a fluoπnation apparatus fined with a drying tube filled with soda lime Elemental fluorine (165 mmol ) as a 10% mixture in dry nitrogen was then passed through the stined solution using nanow bore PTFE tubing at ca 40 mhmin After the fluorine had been added, the solution was poured into 10% aqueous sodium metabisulfite solution (300 ml ). neutralised with solid sodium bicarbonate and continuousiv extracted with dichloromethane The organic extracts were dried and evaporated to a y ellow oil which wa^ identified as 2-fluoropyπdιne (6.5g. 56% ) in -95% purity bv GC. (δ H ,200MHz. CDC1 ,. Me,S l ι 6 9ppm ( lH. m) ".2 ( 1 H. ). 7 8 (1H. m ) 8 2 ( 1H. m). (C (50MHz. CDC. Me,Sι ) 10°- 4ppm (d. : J c . F 37 1. 3-C ). 121 3 (d 4 J c . r 4 2. 5-C ). 141.2 (d. 'J c . F 7 7 4-C). 14 " 5 ( d : J C , 14 5 6-C ι 163 5 (dΛl c . r 237 4. 2-C ) (δ (235MHz. CDC1,. CFC1-,) -67 9ppm ( s. 2-F ) m z (El -) 97 (M .100%).70 (68).69 (12).57 (18).50 (29).39 (22) Example 2 Preparation of 4.7-dιchloroquιno ne without use of base A solution containing 4.7-dιchloroquιnohne (l.Og.5mmol) and iodine (1.28g.5mmol) in CF : C1CFC] : (30ml) was placed in a fluoπnation apparatus fitted with a dry ing tube filled with soda lime Elemental fluorine (7mmol) as a 10% mixture by volume in dry nitrogen was then passed through the stirred solution using narrow bore PTFE tubing at ca 15ml/mιn After the fluoπne had been added, the solution was poured into 10% aqueous sodium metabisulfite solution (30ml) and extracted with dichloromethane The organic extracts were dried and evaporated to an oil (098g) GC'MS analysis showed a 34% conversion oi starting material Column chromatograph} on silica gel with dichloromethane as eluant gav e 2-fluoro-4.7- dichloroquinohne (0.33g.87%) as white crystals, other data were the same as that described in the following reaction Example 3 Fluoπnation of 4.7-dιchloroquιnolιne with use of base A solution containing 4.7-dιchloroquιnolιne (1 Og.5mmol). iodine (1.28g.5mmol) and tπethylamine (0.5 lg.5 lmmol) in CF : C1CFC1 2 (30ml) was placed in a fluoπnation apparatus fitted with a dry ing tube filled with soda lime Elemental fluonne (7mmol i as a 10% mixture in dn nitrogen was then passed through the stirred solution using narrow bore PTFE tubing at ca 15ml/mιn After the fluorine had been added, the solution was poured into 10% aqueous sodium metabisulfite solution (30ml) and extracted with dichloromethane The organic extracts were dried and evaporated to a brown oil (106g) GC/MS analysis showed a 69% conversion of starting material Column cnromatography on silica gel with dichlorometnane as eluant gav e 2- fluoro-4.7-dιchloroquιnoiιne (066g.88%) as white crystals, m p 105-106 L C (vacuum sublimation oil bath temp 60 l C <lmmHg). R F 072. (Found C.497. H.1 " . N.63 C Q H 4 CI F\ requires C.500. H.185. Tv 6.5%). δ H (400MHz. CDCI.. Me 4 Sι) 7.20 ppm (1H. d. J H3 F 24. H- 3).7.58 (1H. d d. J H5H „ 9.0. i mH 2.2. H-6).795 (1H d. J H6H > 20. H-8). S 13 (1H. d. J H < Hf 92 H-5) δ (235MHz CDCI.. Me 4 Sι) -60 Opp (s). δ c (100MHz. CDCI.. Mε 4 Sn 11038 (d : l 458. C-3).1236(d.Xl2.3.C-4a).1255 (s. C-6).1276 (d \l 1.2. C-5).1281 (d J 26. C-8ι 1379 (s C-7).1464(dXJ24.6. C-4).1466 (d. 185. C-8a).1609 (d J 244 l.C-2). mz (EX) 215 (MX 100%).217 (61. M " -2).219 (11. M " -4).182(14).180 ( 40) 145 (18) Example 4: Fluorination of 3-bromoquinoline with use of base A solution containing 3-bromoquinoline (l .Og. 4.8mmol ). iodine ( 1 .22g. 4.8mmol ) and triethylamine (0.48g. 4.8mmol ) in CF C1CFC1 2 (30ml ) was placed in a fluorination apparatus fitted with a drying tube filled with soda lime. Elemental fluorine (5mmol I as a 10% mixture in dry nitrogen was then passed through the stirred solution using narrow bore PTFE tubing at ca. 15ml/m_n. After the fluorine had been added the solution was poured into 10% aqueous sodium metabisulfite solution (30ml ) and extracted with dichloromethane. The organic extracts were dried and evaporated to a brown oil (0.95g). GC/MS analysis showed a 56% conversion of starting material. Column chromatography on silica gel with dichloromethane as eluant gave 2- fluoro-3-bromoquinoline (0.52c. 85%): mp 75-76°C (vacuum sublimation oil bath temp. 50°C'<lmmHg) as white needles: R F 0.69 (CH : C1 : ): (Found: C. 47.5: H. 2.1 : N. 6.2. C q H ? NBrF requires: C. 47.8: H. 2.2: N. 6.2%): δ H (400MHz. CDC1 3 . Me 4 Si) 7.55ppm ( 1H. d d. J H5- H6 = i HbM , 8.0. H-6). 7.74 (1H. d d d. J H7.H8 8.4. J H6. „- 7.2. J H5.H - 1.2. H-7). 7.76 ( lH.d. J H5.H6 8.0. H- 5). 7.91 (1H. d d. J H7.H8 8.4. J H6.H8 0-8- H-8). 8.42 (1H. d. J H4.F 8.4. H-4): δ c ( 100MHz. CDC1 3 . Me 4 Si) 104.0 (d. : .T 43.2. C-3). 126.6 (s. C-6). 127.0 (d. 4 J 2.7. C-8). 128.0 (d. 5 .l 1.9. C-5) 128.0 (d. 4 J 2.2. C-4a). 130.9 (d. 5 J 1.1. C-7 . 143.5 (d. 3 J. 3.7. C-4). 144.2 (d. 5 J 15.1. C-8a). 157.3 (d. 'j 238.1. C-2): δ F (235MHz. CDC1 3 . CFC1 3 ) -60.8ppm (s): m/z (ED 225 (MX 100%). 227 (MX 74). 146 (56). 126 (23). 101 (18). 75 (14). Example 5 : Fluorination of 4-Chloroquinoline A solution containing 4-chloroquinoline (l .Og. όmmol ). iodine ( 1 .55g. όmmol ) and triethylamine (0.60g. όmmol ) in CF 2 C1CF1 ; (30ml) was placed in a fluorination apparatus fitted with a drying tube filled with soda lime. Elemental fluorine (7mmol > as a 10% mixture in dry nitrogen was then passed through the stirred solution at room temperature using naπow bore PTFE tubing at 20ml/mιn. After the fluorine had been added the solution was poured into 10% aqueous sodium metabisulfite solution (30ml) and extracted with dichloromethane. The organic extracts were dried and evaporated to a brown oil (1 .01 g ). GC/MS analysis showed a 76% conversion of starting material. Column chromatography on silica gel with dichloromethane as eluant gave 2- fluoro-4-chloroquinoline (0.76g. 90%): m.p 60-61 ϋ C (vacuum sublimation oil bath temp. 50 υ C«lmmHg ) as white needles: R F 0.78 (CH CI 2 ): (Found C. 59.7: H. 2.9: K. 7.6. C-H.NCIF requires: C. 59.5: H. 2.75: N. 7.7%): δ H (400MHz. CDCI-,. Me 4 Si ) 7.20ppm ( 1 H. d. J„ .3.F 2.4. H-3 ).7.62 ( 1 H. d d d. J,„ „, = J H( , „- 4. J Htl H 1.2. H-6).778 ( 1 H. d d d. J Ht , „- = J H7 ll 7.8. J H5 „- 1.2. H-7).7.96 (1H. d. J H7HR S4. H-8).819 (1H. d. H H5 H 84. H-5). δ F (235MH,. CDCI-,. CFCl- -61.5pm (s). δ c (100MH 7 . CDCI-,. Me 4 Sι) 110.2ppm (d. : .I 45.8. C-3).124.2 (d. \l 0.8. C- 5).125.1 (d. 4 26. C-4a).127.0 (d J 2.7. C-6).128.5 (d. .l 1.5. C-8).1316 (s. C-7).145.9 (d. Xl 18. C-8a).146.6 (d. J .l 12.5. C-4).160.2 (d. 'j 242.3. C-2). nvz (Ef) 183 (MX 26%).181 (MX 100%).146(35).126(15).75(12).50(11) Example 6 Fluorination of 6-Chloroquιnolme A solution containing 6-chloroquιnohne (l.Og.6.1 mmol). iodine (1.55g.6 lmmol) and triethylamine (0.62g.6.2mmol) in CF 2 C1CFC1 2 (30ml) was placed in a fluoπnation apparatus fitted with a drying tube filled with soda lime Elemental fluorine (7mmol ) as a 10% mixture in dry nitrogen was then passed through the stmed solution using narrow bore PTFE tubing at ca 15ml/mιn After the fluorine had been added the solution was poured into 10% aqueous sodium metabisulfite solution (30ml) and extracted with dichloromethane The organic extracts were dried and evaporated to a brown solid (1.03g) GC/MS analysis showed a 79% conversion of starting material Column chromatography on silica gel with dichloromethane as eluant gave 2-fluoro-6-chloroquιnohne (0.82g.93%). R F 0.78 (CH 2 C1 2 ). δ H (400MHz CDC1 3 . Me 4 Sι) 712ppm ( 1H. d d. J H3 H4 8.8. J H3 F 2.8. H-3).767 (1H. d d. J H7 H 9.2. J H5 H - 24. H-7).7.82 (1H. d. J H5H - - . H-5). X87 (1H. d. J H7 90. H-8).8.16 (1H. d d. J^ H4 = J H F 8.8. H-4).δ c ( 100MHz. CDCI-,. Me 4 Sι) 11 l.lppm (d. : J 42.3. C-3).126.3 (s. C-5).127.3 (s. C-4a).129.6 (s C-8).1314 is. C-7).1319(s. C-6) 1410 (d. M 99. C-4).144.1 (d J 16.8. C-8a).161.2 (d. X 2438. C-2). δ F (235MHz. CDC1 3 . CFC1,)-615ppm (s). m z (Ef) 181 (MX 100%).183(M 32ι 146(34).126(11) Example n Fluoπnation of Phenanthπdme with use of base A solution containing phenanthπdine ( 1.0g.56mmol ). iodine ( 14g.56mmo! I and tπethy laminc (056g.5.ommol) in CF 2 C1CFC1 2 (30ml) was placed in a fluorination apparatus fined with a dr ing tube filled with soda me Elemental fluorine (7mmol) as a 10% mixture in dry nitrogen was then passed through the stmed solution using naπow bore PTFE tubing at ca 15ml'mm After the fluorine had been added the solution was poured into 10% aqueous sodium metabisulfite solution (30ml ) and extracted with dichloromethane The orcanic extracts were dried and evaporated to a brown oil (0.92g). GC/MS analysis showed a 53° conversion of starting material. Column chromatography on silica gel with dichloromethane as eluant gave 6- fluoro-phenanthridine (0.39g.67%). R F 0.78 (CH 2 C1 2 ): δ„ (400MH Z . CDCI.. Me 4 Si) 7.61ppm (1H. d d d. J HI I[2 = JHZ H? = 7.8. J^. H , 1.2. H-2).7.69 (2H. m. H-3 and H-9).7.88 (1H. d d d. J H7.H8 8.4. J H8.H o 7.2. J H8 .Hio 1-4. H-8).7.97 (1H. d d. J H3.H 8.0. J H2.H4 X-- H-4).8.21 (1H. d d. J H9 . HIO -0. J HS . HIO 1- . H-10) 8.45 (1H. d d. J HKH2 8.0. J HUH3 0.8. H-l).8.52 ( 1H. d d. J H7.H8 8.4 J H7HQ 1.2. H-7): δ F (376MHz. CDC1 3 . CFC1 3 ).68.2ppm (s): δ c (100MHz. CDC1. Me 4 Si) 117.3ppm(d. : J35.1.C-6a).122.2 (d. 3 J 3.8. C-7).122.2 (s. C-l ).123.9 (d. XT 1.9. C-lOb).124.2 (s. C-10).126.5. (dΛT 2.3. C-2).127.9 (s. C-9).128.7 (d. 4 .l 1.6. C-4).129.4 (s. C-3).132.1 is. C- 8).136.5 (d. 3 J 7.2. C-lOa).141.5 (d. XT 17.9. C-4a).158.1 (d. 'j 248.7. C-61: m/z (Ef) 197 (MX 100%). Example 8: Fluorination of 4-ethvl-pvridine A solution containing 4-ethylpyridine (12.8g.120mmol) and iodine (30.5c.120mmol) in CF 2 C1CFC1 2 (150ml) was placed in a fluorination apparatus fitted with a drying tube filled with soda lime. Elemental fluorine (165mmol) as a 10% mixture in dry nitrogen was then passed through the stirred solution using narrow bore PTFE tubing at ca.40ml/min. After the fluorine had been added the solution was poured into 10% aqueous sodium metabisulfite solution (300ml). neutralised with solid sodium bicarbonate and extracted with dichloromethane. The organic extracts were dried and evaporated to a yellow oil (9.54g ) which contained ethlpyridine (78% conversion).2-fluoropyridine and other minor products by GC/MS. The oil redissolved in dichloromethane and washed with 2N HCI solution, dried (MgS0 4 ) and evaporated to a clear oil to give 2-fluoro-4-ethylpyridιne in >95% purity (6.3g.54% based on 78% conversion): ό H (200MHz. CDCI-.. Me Si) 1.26ppm (3H. t. J 7.6. CH 3 ).2.69 (2H. q. J 7.6. CH 2 ).6.75 (1H. s. H- 3).7.02 (1H. d m. J 5.1. H-5).8.09 (1H. d. J 5.1. H-6): δ c (50MHz. CDCX. Me 4 Si) 14.1ppm is. CH 3 ).28.2 (d. \I C . 2.7. CH ).108.5 (d. 2 J C . F 36.5. C-3).121.3 (d. 4 J C . F 3.9. C-5).147.3 id. ' .I c . : 15.2. C-6).159.3 (d. :, J C ., 7.8. C-4).164.2 (d. 'j c . r 236.3. C-2): δ F (235MHz. CDC1..CFC1-L 69.9ppm(s):m'z(Er) 125 (MX 100%).110 (47).97 (15).83 (13). hxample *V: Huoπnation of quinohne A solution containing quinohne ( 10.6g. 82.5mmol) and iodine (2 l .Og. 82.5mmol ) in CF 2 C1CFC1 : ( 150ml) was placed in a fluorination apparatus fitted with a drying tube filled with soda lime. Elemental fluorine ( 165mmol ) as a 10% mixture in nitrogen was then passed through the stirred solution using a narrow bore PTFE tubing at ca. 40ml min ' . After the fluorine had been added the solution was poured into aqueous sodium metabisulphite solution (300ml ). neutralised with sodium bicarbonate and extracted with dichloromethane. The organic extracts were dried (MgS0 4 ) and evaporated to leave an oil (7.2g). Distillation afforded 2-fluoroquinoline (6.5g. 54%) as a pale yellow oil: b.p 30 . 134-136°C (lit., b.p 30 133°C): δ H (400MHz: CDC1 : Me 4 Si ) 7.05ppm (IH. d d. J H3 H 8.8. J H3.F 2.8. H-3). 7.51 (IH. d d d. J H5.H6 8.0. J Hc H - 6.8. J H6.H8 0-8- H-6). 7.71 (I H. d d d. J H7-H8 8.0. J H6.H - 7.6. J H5 H - 1.2. H-7). 7.81 (I H. d. J H;.Hp 8.0. H-5). 7.94 ( IH. d. J H7 HS 8.4. H-8). 8.20 ( IH. d d. J^^ = -Vr 8.4. H-4): δ F (250MHz: CDCI,: Me 4 Si) -63.2 ppm: δ c ( 100MHz. CDCI,. Me 4 Si ) 1 10.0 ppm (d. : .T 42.1. C-3). 126.1 id. 4 J 2.6. C-8). 126.8 (d. 4 1.9. C-4a). 127.5 (s. C-6). 128.0 (d. 5 J 1.2. C-5). 130.6 (d. 5 J 0.8. C-7). 141.9 (d. 3 J 9.9. C-4). 145.7 (d. :, J 16.7. C-8a). 161.1 (d 'j 240.5. C-2): m/z (Ef) 147 (MX 100%). Example 10: Fluorination of 3-bromoquinoline without use of base A solution containing 3-bromoquinoline ( l .Og. 4.8mmol ) and iodine (1.22g. 4.8mmol ) in CF C1CFC1 2 (30ml ) was placed in a fluorination apparatus fitted with a drying tube filled with soda lime. Elemental fluorine (5mmol ) as a 10% mixture in dry nitrogen was then passed through the stirred solution using narrow bore PTFE tubing at ca. 15ml/mm. After the fluorine had been added the solution was poured into 10% aqueous sodium metaisulfite solution (30ml ) and extracted with dichloromethane. The organic extracts were dried and evaporated to a brown oil (0.92g) GC'MS analysis showed a 43% conversion of starting material Column chromatography on silica gel with dichloromethane as eluant gave 2-fluoro-3-bromoquinohne (0.35c. 74% ι: m.p. 75-76°C ( vacuum sublimation oil bath temp. 50"C <lmmHg ) as white needles: R F 0.69 (CH 2 C1 2 ): (Found: C. 47.5: H. 2.1 : N. 6.2. C 0 H,NBrF requires: C. 47.8: H. 2.2: N. 6.2%): δ H (400MHz. CDCI,. Me 4 Si) 7.55ppm (IH. d d. J H5 H , = r 8.0. H-6). 7.74 (IH. d d d. HS 8.4. J H6.H - --• J H5 . M - ! •-■ H " 7 )- " .76 ( I H. d. J H5.H 8.0. H-5 ). 7.91 ( I H. d d. J„-. HS 8.4. J Hb.Hj . 0.8. H-8 ). 8.42 (IH. d. J H .F 8.4. H-4 ): δ c ( 100MHz. CDCI,. Me 4 Si i 1 04.0 (d. : .l 43.2. C-3 ). 126.6 ( s. C-6). 127.0 (d. 4 .1 2.7. C-8 ). 128.0 ( dX.T 1.9. C-5 ) 128.0 (d. J 2.2. C-4a). 130.9 ( d. XT 1 .1. C-7). 143.5 ( d. ' .T 3.7. C-4). 144.2 IdX.l 15.1. C-8a). 157.3 (d '.1 238.1. C-2): δ, (235MHz. CDCI,. CFCl 3 ) -60.8ppm (s): m/z (Ef ) 225 (MX 100%). 227 (MX 74 ). 146 (56). 126 (23 ). 101 ( 18). 75 (14). Example 1 1 : Fluorination of 4-chloro-7-trifluoromethylquinoline A solution containing 4-chloro-7-trifluoromethyl-quinoline ( l .Og. 4.3mmol) and iodine ( l . l g. 4.3mmol in CF 2 C1CFC1 (30ml) was placed in a fluorination apparatus fitted with a drying tube filled with soda lime. Elemental fluorine (5mmol) as a 10% mixture in dr nitrogen was then passed through the stirred solution using narrow bore PTFE tubing at ca. 15ml/'min. After the fluorine had been added the solution was poured into 10% aqueous sodium metablsuifite solution (30ml). neutralised with solid sodium bicarbonate and extracted with dichloromethane. The organic extracts were dried and evaporated to a yellow solid (1.09g). GC MS analysis showed a 5% conversion of starting material. Column chromatography on silica gel with dichloromethane as eluant gave 2-fluoro-4-chloro-7-trifluoromethy -quinoline (0.05g. 86%): m.p. 94-95°C (vacuum sublimation oil bath temp. 50°C/<lmmHg) as white needles: R F 0.69 (CH 2 C1 2 ): (Found C. 47.7: H. 1.3: N. 5.5. C 10 H 4 NC1F 4 requires: C. 48.1 : H. 1.6: N. 5.6%): δ H (400MHz. CDCI,. Me 4 Si) 7.32 ppm (IH. d. J H.F 2.4. H-3). 7.79 (IH. d d. J H5 . H6 8.8. J H6.H8 1 -6- H-6). 8.23 (IH. m. H- 8). 8.32 ( IH. d. J H5.H6 8.8. H-5): δ c (50MHz. CDC1 3 . Me 4 Si) 1 12.3 ppm (d. : J CF 45.5. C-2). 122.9 im. C-6). 123.4 (q. 'j CF 272.7. CF 3 ). 125.6 (s. C-5). 126.2 (m. C-8). 126.7 (s. C-4a). 133.4 q. : J CF 33.2. C-7). 145.2 (d. 3 J CF 18.7. C-8a). 146.7 (d. J CF 12.9. C-4). 160.9 (d. 'j CF 245.3. C-2 ): δ F (235MHz. CDCI,. CFC1, -55.0ppm (IF. s. F-2). -59.2 (3F. s. CF 3 ): m/z (Ef ) 249 (MX 100%). 251 (MX 33 ). 230 (26). 214 ( 18). 201 (1 1 ). 199 (33 ). 194 ( 12 ). 145(26). 99 (19). Example 12: Fluorination of Phenanthridine without use of base A solution containing phenanthridine (l .Og. 5.6mmol ) and iodine ( 1.4g. 5.6mmol ) in CF 2 C1CFC1 2 (30ml I was placed in a fluorination apparatus fitted with a drying tube filled with soda lime. Elemental fluorine (7mmol ) as a 10% mixture in dry nitrogen was then passed through the stmed solution using nanow bore PTFE tubing at ca. 15ml mιn. After the fluorine had been added the solution was poured into 10% aqueous sodium metabisulfite solution (30ml > and extracted with dichloromethane. The organic extracts were dried and evaporated to an oranee oil (0.91 ). GC/MS analvsis showed a 17% conversion of staπinc material. Column chromatography on silica get with dichloromethane as eluant gave 6-fluoro-phenanthridιne (0.09g.48%); R, 0.78 (CH C1 2 ): δ„ (400MHz. CDCI,. Me 4 Si) 7.61 ppm (IH. d d d. J HUI2 = l ir _ M = 7.8..1 H2H4 1.2. H-2).7.69 (2H. m. H-3 and H-9).7.88 (IH. d d d. J H , .HS 84. J H8.H4 .2. J H8H1(ι 1.4. H-8).7.97 (IH. d d..T H . 4 8.0. J H H4 1.2. H-4).8.21 (IH. d d. J H9HI0 8.0. J Hg-HI( , 1.4. H-10_ 8.45 (IH. d d. i H H2 8.0. J H H? 0.8. H-l ).8.52 (IH. d d. J H7 H8 8.4. J H7 HQ 1.2. H-7): δ r (376MHz. CDCI,. CFC1,) -68.2ppm (s): δ c (100MHz. CDCI,. Me 4 Sl) 117.3ppm (d. : .l 35.1.C-6a).122.2 (d. 3 J 3.8. C-7).122.2 is. C-l).123.9 (d. J 1.9. C-lOb).124.2 (s. C-10).126.5 id. 6 J 2.3. C-2).127.9 (s. C-9).128.7 (d. 4 J 1.6. C-4).129.4 (s. C-3).132.1 (s. C-8).136.5 (d. .T 7.2. C-lOa). 141.5 (d. .T 17.9. C-4a).158.1 (d. '.1248.7. C-6): m/z (Ef) 197 (M * .100%ι. Example 1 : Fluorination of quinoxaline A solution containing quinoxaline (15.6g).120mmol) and iodine (30.5g.120mmol) in CFC1CFC1 (150ml) was placed in a fluorination apparatus fitted with a drying tube filled with soda lime. Elemental fluorine (165mmol) as a 10% mixture in nitrogen was then passed through the stirred solution using narrow bore PTFE tubing at ca.40ml/min. After the fluorine had been added the solution was poured into 10% aqueous sodium metabisulfite solution (300ml). neutralised with sodium bicarbonate and continuously extracted with dichloromethane for 24 hours. The organic extracts were dried and evaporated to an oil (13.6g). GC/MS analysis showed a 49% conversion of quinoxaline. The oil was purified by column chromatography on silica gel using dichloromethane as eluant to give pure 2-fluoroquinoxaline as a pale yellow oil (5.30g.62% based on 49% conversion): R F 0.53: δ H (200MHz: CDCI, Me 4 Si) 7.7ppm (2H. m). 7.9 (IH. m).8.1 (IH. m).8.67 (IH. d. J H.F 7.9. H-3): δ F (250MHz: CDCI,: Me 4 Si) -75.1 pp isi. δ c (50.3MHz. CDC13. Me 4 Si) 128.4ppm (d. J C 1.6. C-8).129.4 (s. C-7).129.45 (s. C-6).131.. is. C-5).136.5 Id. : J CF 42.6. C-3).139.72 Id. J C[ 10.9. C-8a).141.52 (d J CF 1.8. C-4a).156.74 (d. 'J C.F 256.0. C-2): m'zfET) 148 (M-.100).129(20).121 (12).103(17).76.24).50 -.171. and 2.3-difluoroqumoxaime (0.27g.3%) as a pale yellow solid: R F 0.75: δ H (400MHz. CDCI,. Me_Si) 7.79ppm (2H. m. Ar-H).7.99 (2H. m. Ar-H). δ c (50MHz. CDCI,. Me 4 Si) 127.8 (s. C-8). 130.4 is. C-7).130.4 is. C-7).138.4 (d d. J C . F 5.4. C-4a).146.1 (dd. 'j . F 261.3. : J C ., 39.5. C-2). δ F (235MHz. CDCI,. CFC1 3 ) -82.8ppm (si: nrz (Ef) 166 (MX 100%).139 (11 ).

Claims: CLAIMS 1 A method of preparing a heterocyclic organic compound having at least one fluoπne substituent in the heterocyclic ring, the method comprising the step of reacting a heterocyclic compound with elemental fluorine in the presence of another halogen 2 A method according to Claim 1 wherein the heterocyclic compounα includes a five or six membered heterocyclic ring which may optionally contain substituents 3 A method according to Claim 1 or Claim 2 wherein the heterocyclic compound includes a six-membered aromatic ring containing one or more nitrogen atoms, the ring being optionally attached or benzofused to one or more other aromatic rings 4 A method according to Claim 3 wherein the heterocyclic compound is selected from pyridine. pynmidine. pyπdazine. pyrazine. tπazine. quinohne. isoquinoline. quinoxaline. quinazo ne and bipyridine 5. A method according to any of the preceding Claims wherein the other halogen is selected from one or more of 1. Br. Cl and mterhalogen compounds 6 A method according to any of the preceding Claims wherein the elemental fluoπne is delivered to the heterocyclic compound in an inert gas 7 A method according to any of the preceding Claims wherein the heterocyclic compound is contained in an organic solvent which also contains the other halogen, fluorine being passed into the organic solvent 8 A method according to Claim 7 wherein the organic solvent is a fluormated organic solvent 9 A method according to any of the preceding Claims wherein a base is added to the reaction medium 10 A method according to Claim 9 wherein the base is selected from tπεthylamine. tπbutylamine. N-methy lpipeπdine. sodium fluoride and potassium fluoride

Inventors: CHAMBERS RICHARD DICKINSON, SANDFORD GRAHAM, CHAMBERS, RICHARD, DICKINSON, SANDFORD, GRAHAM
Applicants: BNFL FLUORCHEM LTD, CHAMBERS RICHARD DICKINSON, SANDFORD GRAHAM, BNFL FLUOROCHEMICALS LTD., CHAMBERS, RICHARD, DICKINSON, SANDFORD, GRAHAM
Application year: 1995
Main classification: C07D213
IPC codes: C07D213, C07D215, C07D221, C07D239, C07D241