CARBOXYLATES AND ITS DERIVATIVES

FIELD OF THE INVENTION

The present invention relates to a one pot, simple, cost effective and industrially feasible catalytic synthesis of 3-substituted quinoline carboxylates and its derivatives from anilines with yield >80%.

BACKGROUND OF THE INVENTION

Quinoline, a heterocyclic aromatic organic compound though itself has few applications, however, its derivatives are useful in diverse applications. The prominent example is quinine which is found naturally in plants as alkaloids. 4-Hydroxy-2- alkylquinolines (HAQs) and are involved in antibiotic resistance. Quinolines are used as bio actives and drugs. Ester products can be hydrolyzed to obtain other products.

There is ample literature available on the methods for synthesis of quinolines or substituted quinolines using aniline.

Article titled, "Synthesis of 2,4-unsubstituted quinoline-3-carboxylic acid ethyl esters from arylmethyl azides via a domino process" by Jumreang Tummatorn, Charnsak Thongsornkleeb, Somsak Ruchirawat and Tanita Gettongsong in Org. Biomol. Chem., 2013, 11, 1463-1467 reports the synthesis that employs arylmethyl azides as the precursor which undergoes an acid-promoted rearrangement to give an N-aryl iminium ion. Following, the addition with ethyl 3-ethoxyacrylate intramolecular electrophilic aromatic substitution, elimination and subsequent oxidation yielded quinoline derivatives as shown below in Scheme A.

Scheme: A

5 Article titled, "A One-Step Synthesis of 2,4-Unsubsti uied Quinoiifl.e-3-carboxylic Acid Esters .from o-Nitrobenzaidehydes" by Hariharan Veakatesan, Frances M. Hocutt. Todd K, Jones, and Michael abinowi ? in J, Org, Chem. 2010, 75, ^' 34BS-3491 reports reductive cyclizaiion earned out by treating various substituted o-nitro benza!dehydes with commercially availablc\i,3~diethoxypropion;e acid ethyl ester and SnC¾, 21¾0 in 10 reiluxing ethanoL {Scheme B),

Scheme: B iron- catalyzed intramolecular allylie ammation of ^' 2-ammophenyH -en-3-ols to afford I S l,2-dihydroquinoHn.e and quaioliue derivatives under mild reaction conditions by Z.

Wang, S. Li, B. Wu et. al is disclosed in J. Org. Chem,, 2012, 77, 861 5-8620. (Scheme C)

Scheme: C

Article titled "A Simple and Convenient Copper-Catalyzed Tandem Synthesis of Quinoline-2-carboxylates at Room Temperature" by He. Huang, H. Jiang, K. Chen, H. Liu, J. Org. Chem., 2009, 74, 5476-5480 disclose copper-catalyzed synthesis of quinoline-2-carboxylate derivatives through sequential intermolecular addition of alkynes onto imines and subsequent intramolecular ring closure by arylation at room temperature.(Scheme D)

Scheme: D

Article titled,"Enamine formation from anilines and methyl propiolate. The synthesis of 4(lA)-quinolones" by Ned D. Heindel, Peter D. ennewell and Velmer B. Fish in Journal of Heterocyclic Chemistry Volume 6, Issue 1, pages 77-81, February 1 69 reports a process of addition of substituted anilines to methyl propiolate which produces labile cis-trans mixtures of enamines which can be isomerized by acid, solvent variation, and thermal techniques. Thermal cyclization of these enamines provides a synthesis of 4( lH)-quinolones Article titled,"Catalytic Radical Cation Salt Induced C _sp ³ -H Functionalization of Glycine Derivatives: Synthesis of Substituted Quinolines" Xiaodong Jia,* Fangfang Peng, Chang Qing, Congde Huo, and Xicun Wang, Org. Lett., 2012, Vol. 14{\5), 4030- 4033 reports a domino C _sp ³ -H functionalization of glycine derivatives under catalytic radical cation salt induced conditions, producing a series of quinolines.

Article titled, "Synthesis of 2,3-disubstituted quinolines from in situ generated imines and its enamine tautomer under radical cation induced conditions" by Xiaodong Jia , Fangfang Peng, Chang Qing, Congde Huo, Yaxin Wang, Xicun Wang in Tetrahedron Letters, Volume 54, Issue 36, 4 September 2013, Pages 4950-4952 reports a tandem cyclization/aromatization of anilines and aldehydes under catalytic radical cation salt induced conditions, producing a series of 2,3-disubstituted quinolines in good yields.

Article titled, "Palladium-catalyzed synthesis of polysubstituted quinolines from 2- amino aromatic ketones and alkynes" by Wang Zhou and Jianhua Lei in Chem. Commur , 2014,50, 5583-5585 reports a palladium-catalyzed one-pot method for the synthesis of quinolines from commercial or readily available 2-amino aromatic ketones and alkynes (Scheme E).

1 2 3

27 examples

yields up to 89%

Scheme: E

Article titled, "Rh-Catalyzed Sequential Hydroarylation/Hydrovinylation- Heterocyclization of p-(2-Aminophenyl)-a,p-ynones with Organoboron Derivatives: A New Approach to Functionalized Quinolines" by G. Abbiati, A. Arcadi, F. Marinelli, E. Rossi, M. Verdecchia in Synlett, 2006, 3218-3224 reports a process for synthesis of 4- Aryl and 4-vinyl quinolines via a sequential procedure involving regioselective rhodium-catalyzed hydroarylation/ hydrovinylation of p-(2-aminophenyl)-a,P-ynones with arylboronic acids or potassium aryl and vinyl trifluoroborates, followed by nucleophilic attack of the amino group onto the carbonyl (Scheme F).

Scheme: F

US3567732 discloses a process for the preparation of chlorinated quinolines of the formula wherein the chlorine attached to the benzene nucleus is in a position selected from the group consisting of the 5, 6, 7 and 8 positions. The said process involves reacting a 2, 3 or 4-chloroaniline with a compound selected from the group consisting of B-propiolactone and a. compound of the formula wherein R is selected from the group consisting of hydrogen and lower alkyl, cycliz ng the 3-(chloroanilino)- propionic acid formed with polyphosphoric acid, chlorinating the resulting 5, 6, 7 or 8-chloro-4- oxo- 1,2,3,4- tetrahy droquinoline with phosphorus oxychloride and recovering said chlorinated quinoline. Article titled, "Selective Reduction of Nitroarenes by a Hantzsch 1,4-Dihydropyridine: A Facile and Efficient Approach to Substituted Quinolines" by J. Horn, S. P. Marsden, A. Nelson, D. House, G. G. Weingarten in Org. Lett., 2008, 10, 41 17-4120 reports an efficient reductive cyclization of o-nitrocinnamoyl compounds was achieved by employing Hantzsch 1 ,4-dihydropyridine diethyl ester as a biomimetic reducing agent in the presence of catalytic palladium on carbon. This approach was successfully applied to the synthesis of substituted quinolones (Scheme G).

Scheme: G

The processes disclosed in the art are lengthy, cumbersome, cost-ineffective, have low selectivity and yields.

OBJECTS OF THE INVENTION

The main object of the present invention is to provide a one pot, simple, cost effective and industrially feasible process for the synthesis of 3 -substituted quinoline carboxylates and its derivatives from anilines with yield > 80%.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides a one pot process for the preparation of compound of formula I

wherein Ri, R ₂ and R ₃ are each independently selected from the group consisting of hydrogen, substituted or unsubstituted alkyl (C1-C4), substituted or unsubstituted alkenyl (C1-C4), substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, hydroxy, alkoxy and halogen; or Ri and R2 together form a fused cyclic aromatic or aliphatic ring optionally substituted with one or two heteroatoms; and

R4 is selected from the group consisting of lower alkyl (C1-C4) and aryl; the process comprising the step of: reacting a compound of formula II at a temperature in the range of 20 to 30°C for 5 to 6 hours in presence of formic acid and a compound of formula III using rhodium acetate as a catalyst to obtain compound of Formula I,

wherein Ri, R ₂ and R3 are each independently selected from the group consisting of hydrogen, substituted or unsubstituted alkyl (C1-C4), substituted or unsubstituted alkenyl (C1-C4), substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, hydroxy, alkoxy and halogen; or R _\ and R ₂ together form a fused cyclic aromatic or aliphatic ring optionally substituted with one or two heteroatoms; and

R4 is selected from the group consisting of lower alkyl (C1-C4) and aryl.

In an embodiment of the present invention, compound of formula I is selected from the group consisting of:

Ethyl 5,7-dimethoxy quinoline-3-carboxylate (la);

Ethyl [l,3]dioxolo[4,5-G]quinoline-7-carboxylate (lb); Ethyl 7-methoxy quinoline-3-carboxylate (Ic);

Ethyl benzo[h]quinoline-3-carboxylate (Id);

Ethyl 7-methoxy-6-methylquinoline-3-carboxylate (Ie);

Methyl benzo[h]quinoline-3-carboxylate (If);

Ethyl 5,6,7-trimethoxyquinoline-3-carboxylate (Ig); and

Ethyl 8-bromo-5,7-dimethoxyquinoline-3-carboxylate (Ih).

In another embodiment of the present invention, the catalyst used is recyclable.

In yet another embodiment of the present invention, the reaction is carried out under nitrogen atmosphere.

In yet another embodiment of the present invention, preparation of 3-substituted carboxylate quinoline compounds of formula I (Ia-Ih) comprising the steps of:

reacting aniline compounds of Formula Ila-IIe, Ilh and Hi in presence of formic acid and ethyl propynoate using rhodium acetate as a catalyst to obtain 3-substituted carboxylate quinoline compound of formula Ia-Ih, with > 80% yield.

lid lie Ilh

In yet another embodiment of the present invention, said process further comprises subjecting quinoline carboxylate compound of formula lb to N-alkylation with ethyl trifluoromethane sulfonate followed by oxidation with K ₃ Fe(CN) ₆ to obtain oxolinic acid of formula (IV)

wherein the yield of said oxolinic acid is >45%.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a one pot, simple, cost effective and industrially feasible synthesis of 3-substituted quinoline carboxylates and its derivatives from anilines using a a recyclable catalyst with yield > 80%.

The present invention discloses a one pot synthesis of quinolines or substituted quinolines via formylation followed by rhodium catalyzed net C-H insertion ortho to the anilines of formula (I).

wherein Ri, R2 and R ₃ are each independently selected from the group consisting of hydrogen, substituted or unsubstituted alkyl (C1-C4), substituted or unsubstituted alkenyl (C1-C4), substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, hydroxy, alkoxy and halogen; or Ri and R ₂ together form a fused cyclic aromatic or aliphatic ring optionally substituted with one or two heteroatoms; and

R4 is selected from the group consisting of lower alkyl (C1-C4) and aryl.

The present invention provides a one pot synthesis of compound of Formula I, comprising:

reacting a compound of Formula II with a compound of Formula III in presence of formic acid using Rh acetate as a catalyst to obtain 3-substituted quinoline carboxylates and its derivatives of Formula I with yield >80% .

The above process is shown below in Scheme 1 :

Scheme: 1

wherein R|, R ₂ and R3 are each independently selected from the group consisting of hydrogen, substituted or unsubstituted alkyl (C1-C4), substituted or unsubstituted alkenyl (C1-C4), substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, hydroxy, alkoxy and halogen;

or Ri and R ₂ together form a fused cyclic aromatic or aliphatic ring optionally substituted with one or two heteroatoms; and

R4 is selected from the group consisting of lower alkyl (C1-C4) and aryl.

The present invention provides a process for the preperation of compound of formula I (Ia-Ih) from substituted aniline (Ila-IIe, Ilh and Hi) and ethyl propynoate comprising reacting aniline (Formula Ila-IIe, Ilh and Hi) in presence of formic acid and ethyl propynoate using Rh acetate as a catalyst.

Structures of aniline Ila-IIe, lib. and Hi

The catalyst used in the process is recyclable thus making the process cost effective and industrially feasible.

The compound of formula I, is selected from the group consisting of:

Ethyl 5,7-dimethoxy quinoline-3-carboxylate;

la

Ethyl [l,3]dioxolo[4,5-G]quinoline-7-carboxylate;

lb Ethyl 7-methoxy quinoline-3-carboxylate;

Ic

Ethyl benzo[h]quinoline-3-carboxylate;

Id

Ethyl 7-methoxy-6-methylquinoline-3-carboxylate;

Ie

Methyl benzo[h]quinoline-3-carboxylate;

If

Ethyl 5,6,7-trimethoxyquinoline-3-carboxylate; and Ethyl 8-bromo-5,7-dimethoxyquinoline-3-carboxylate;

Ih.

The process of the present invention is carried out at room temperature in the range of 20 to 30°C for a time period in the range of 4 to 6 hrs and reaction is carried under nitrogen atmosphere.

The present invention further provides a process wherein the 3 -substituted carboxylate quinoline compound of formula I prepared by the process of the present invention is used for the synthesis of oxolinic acid (IV),

using 3-substituted carboxylate quinoline compound of formula lb.

The present invention provides a single step process for the synthesis of oxolinic acid (IV) with yield > 45%, wherein said process comprises subjecting compound of formula lb to N-alkylation with ethyl trifluoromethane sulfonate followed by oxidation with K.3Fe(CN) ₆ to give oxolinic acid (IV).

The above process is shown below in Scheme 2:

Scheme: 2

The oxolinic acid (IV) prepared by the process of the present invention is a quinolone antibiotic and antibacterial used in treatment of urinary tract infections and psoriasis.

EXAMPLES

The following examples are given by way of illustration and therefore should not be construed to limit the scope of the invention.

Example 1

General experimental procedure for the preperation of 3-substituted carboxylate quinoline

To a mixture of substituted aniline (Ila-IIh) (0.1 g, 1 mmol), Rh ₂ (OAc)4 (2.5 mol %) and formic acid (1 mL) under a nitrogen atmosphere was added followed by ethyl propynoate (Ilia) (1.5 mmol). The resulting brown/purple solution was stirred at room temperature i.e. 25°C for 4-6 h then diluted with ethyl acetate (10 mL), and washed with water (10 mL), 5% aqueous sodium bicarbonate (15 mL), and brine (10 mL). The organic layer was dried (Na ₂ S0 ₄ ) and concentrated in vacuum to afford a brown solid. Flash chromatography eluting with pet ether and ethyl acetate quinoline 3-carboxylic acid ester (Ia-Ih) as a solid. Example 2

Ethyl 5,7-dimethoxy quinoline-3-carboxylate (la)

Yield: 85%, colorless solid, mp 122-123 °C; IR (CHC1 ₃ , cm ^"1 ): t 1722, 1618, 1599, 1505, 1432; Ή NMR (200 MHz, CDC1 ₃ ): δ 1.38 (t, J = 7.3 Hz, 3H), 3.89 (s, 3H), 3.93 (s, 3H), 4.38 (q, J = 7.3 Hz, 2H), 6.43 (s, 1H), 6.98 (s, 1H), 8.97 (s, 1H), 9.24 (s, 1H); ^l3 C NMR (50 MHz, CDCI3): δ 14.5, 55.7, 55.8, 61.1, 98.8, 99.8, 115.6, 120.3, 133.4, 150.9, 152.1, 156.9, 163.5, 165.5; Anal. Calcd for C14H15NO4: C, 64.36; H, 5.79; N, 5.36. Found: C, 64.37; H, 5.85; N, 5.36 %; HRMS (ESI): calc. for [(Ci ₄ H ₁₅ N0 ₄ )H] (M+Na) 284.0895., measured 284.0895.

Example 3

Ethyl [l,3]dioxolo[4,5-<7]quinoline-7-carboxylate (lb)

Yield: 90%, colorless solid, mp: 102-103 °C; IR (CHCI3, cm ^"1 ): T 3081, 1699, 1611, 1277, 1203, 1077; Ή NMR (200 MHz, CDC1 ₃ ): δ 1.45 (t, J = 7.8 Hz, 3H), 4.45 (q, J = 7.1 Hz, 2H), 6.15 (s, 2H), 7.12 (s, 1H), 7.40 (s, 1H), 8.58 (d, J= 2.1 Hz, 1H), 9.21 (d, J = 1.9 Hz, 1H); ^l3 C NMR (50 MHz, CDC1 ₃ ): δ 14.4, 61.2, 102.1, 103.5, 106.0, 122.3, 124.0, 136.8, 148.1, 148.7, 152.5, 161.9, 165.4; Anal. Calcd for C _I3 H _U N0 ₄ : C, 63.67; H, 4.52; N, 5.71. Found: C, 63.67; H, 4.45; N, 5.66 %; HRMS (ESI): calc. for [(Ci ₃ H,,N0 ₄ )H] (M+H) 246.07, measured 246.0764. Example 4

Ethyl 7-methoxy quinoline-3-carboxylate (Ic)

Yield: 81%, Yellow solid, mp: 70-71 °C; IR (CHCI3, cm ^"1 ): t 2981, 1717, 1601, 1279, 1243, 1027; Ή NMR (200 MHz, CDC1 ₃ ): δ 1.46 (t, J = 7.1 Hz, 3H), 3.99 (s, 3H), 4.45 (q, J= 7.8 Hz, 2H), 7.26 (s, 1H), 7.45 (d, J= 2.4 Hz, 1H), 7.79 (d, J= 8.6 Hz, 1H), 8.73 (d, J = 2.1, 1H), 9.36 (d, J = 2.1 Hz, 1H); ¹³ C NMR (50 MHz, CDC1 ₃ ): δ 14.3. 55.6. 60.7, 61.2, 107.0, 107.4, 120.9, 129.6, 130.1, 138.1, 139.9, 150.5, 170.8; Anal. Calcd for ^Η ₁₃ Ν0 ₃ : C, 67.52; H, 5.67; N, 6.06. Found: C, 67.51; H, 5.65; N, 6.06 %; HRMS (ESI): calc. for [(CsHnNC^H] (M+H) 232.09, measured 232.0970.

Example 5

Ethyl benzo[h]quinoline-3-car boxy late (Id)

Yield: 83%, Yellow solid, mp: 111-112 °C; IR (CHCI3, cm ^'1 ): i 2983, 1716, 1598, 1314, 1260, 1212, 750; Ή NMR (200 MHz, CDC1 ₃ ): δ 1.48 (t, J= 7.1 Hz, 3H), 4.48 (q, J= 7.1 Hz, 2H), 7.29-7.32 (m, 1H), 7.72-7.75 (m, 2H), 7.82 (d, J= 8.8 Hz, 1H), 7.89 (d, 7= 1.7, 8.6 Hz, 1H), 8.78 (d, J = 1.8 Hz, 1H), 9.31 (dd, J = 1.8, 7.2 Hz, 1H), 9.51 (d, J = 1.8 Hz, 1H); ^l3 C NMR (50 MHz, CDC1 ₃ ): δ 14.4, 61.3, 123.9, 125.2, 125.4, 127.4, 127.6, 127.8, 128.6, 129.2, 131.2, 134.5, 137.6, 148.9, 149.0, 165.4; Anal. Calcd for C16H13NO2: C, 76.48; H, 5.21; N, 5.57. Found: C, 76.47; H, 5.19; N, 5.56 %; HRMS (ESI): calc. for [(C, ₆ H| ₃ N0 ₂ )H] (M+H) 252.10, measured 252.1023. Example 6

Ethyl 7-methoxy-6-methylquinoline-3-carboxylate (Ie)

Yield: 85%, colorless solid, mp 130-132 °C; IR (CHC1 ₃ , cm ^'1 ): 3081, 1716, 1611, 1299, 1250, 1033; Ή NMR (200 MHz, CDC1 ₃ ): δ 1.40 - 1.52 (t, J = 7.4 Hz, 3H), 2.39 (s, 3H), 4.01 (s, 3H), 4.45 (q, J = 6.9 Hz, 2H), 7.40 (s, 1H), 7.61 (s, 1H), 8.65 (s, 1H), 9.30 (s, 1H); ¹³ C NMR (50 MHz, CDC1 ₃ ): δ 14.4, 16.8, 55.7, 61.0, 106.2, 121.1, 121.7, 129.0, 130.5, 137.2, 149.4, 150.9, 161.6, 165.6; Anal. Calcd for C14H15NO3: C, 68.56; H, 6.16; N, 5.71. Found: C, 68.57; H, 6.15; N, 5.72 %; HRMS (ESI): calc. for [(C ₁₄ Hi ₅ N0 ₃ )H] (M+H) 246.11, measured 246.1127.

Example 7

Methyl benzo[h]quinoline-3-carboxylate (If)

Yield: 85%, colorless solid, mp 124-125 °C IR (CHCI3, cm ^"1 ): i> _max 2980, 1717, 1600, 1374, 1250, 1222, 750; Ή NMR (200 MHz, CDCI3): δ 4.07 (s, 3H), 7.68 - 7.76 (m, 3H), 7.82 (d, J= 8.7 Hz, 1H), 7.87 - 7.91 (m, 1H), 8.71 - 8.81 (m, 1H), 9.28 - 9.35 (m, 1H), 9.43 - 9.54 (m, 1H); ¹³ C NMR (50 MHz, CDCI3): δ 52.4, 123.6, 125.2, 125.4, 125.5, 127.4, 127.8, 128.7, 129.3, 131.1, 134.5, 137.7, 148.9, 148.9, 165.9; Anal. Calcd for CisHnNC^: C, 75.94; H, 4.67; N, 5.90. Found: C, 75.95; H, 4.65; N, 5.89 %; HRMS (ESI): calc. for [(QsHnNC^H] (M+H) 238.08, measured 238.08. Example 8

Ethyl 5,6,7-trimethoxyquinoline-3-carboxylate (Ig)

Yield: 85%, colorless solid, mp 122-123 °C; IR (CHC1 ₃ , cm ^"1 ): _max 3000, 1718, 1607, 1479, 1278, 1020; Ή NMR (200 MHz, CDC1 ₃ ): δ 1.47 (t, J= 7.2 Hz, 3H), 3.97 (s, 3H), 4.04 (s, 3H), 4.12 (s, 3H), 4.47 (q, J = 7.2 Hz, 2H), 7.28 (s, 1H), 8.98 (s, 1H), 9.28 (s, 1H); ^l3 C NMR (50 MHz, CDC1 ₃ ): δ 14.8, 30.0, 56.5, 61.5, 61.0, 104.3, 121.5, 133.4, 141.4, 147.9, 148.0, 148.2, 149.9, 158.4, 165.8; Anal. Calcd for Ci _S Hi ₇ N0 ₅ : C, 61.85; H, 5.88; N, 4.81. Found: C, 61.85; H, 5.85; N, 4.80 %; HRMS (ESI): calc. for [(C ₁₅ Hi ₇ N0 ₅ )H] (M+H) 292.11, measured 292.1184.

Example 9

Ethyl 8-bromo-5,7-dimethoxyquinoline-3-carboxylate (Ih)

Yield: 85%, colorless solid, mp 102-103 °C; IR (CHC1 ₃ , cm ^"1 ): υ _Μ 2987, 1717, 1605, 1478, 1264, 1002; Ή NMR (200 MHz, CDC1 ₃ ): δ 1.46 (t, J= 7.8 Hz, 3H), 4.08 (s, 3H), 4.10 (s, 3H), 4.45 - 4.49 (q, J= 7.1 Hz, 2H), 6.70 (s, 1H), 9.09 (d, J= 1.8 Hz, 1H), 9.48 (d, J = 1.8 Hz, 1H); ¹³ C NMR (50 MHz, CDC1 ₃ ): δ 14.5, 56.1, 56.9, 61.3, 93.9, 94.2, 101.8, 115.9, 121.0, 134.0, 135.6, 152.1, 157.0, 159.3; Anal. Calcd for C _l4 H,4BrN0 ₄ : C, 49.43; H, 4.15; Br, 23.49; N, 4.12. Found: C, 49.42 H, 4.15; Br, 23.49; N, 4.12 %; HRMS (ESI): calc. for [(Ci ₄ Hi ₄ BrN0 ₄ )H] (M+H) 340.01, measured 340.0178. Example 10

SYNTHESIS OF OXOLINIC ACID

A mixture of quinolone (lb) (0.1 g) and ethyl trifluoromethane sulfonate (0.15 g) was warmed at 50 °C for 1 h. After removal of ethyl trifluoromethane sulfonate in vaccuo, the residue was added to a suspension of ₃ Fe(CN)6 (0.25 g) in 20% NaOH (10 mL) and stirred at room temperature for 2 h. The mixture was extracted with ethyl acetate, and the extract was washed with brine and dried over MgS0 ₄ . After removal of ethyl acetate, the residue was purified by silica gel (CH ₂ Cl ₂ :MeOH = 50:1) to give quinolone (IV) (0.053 g, 50%) as a colorless solid.

IV

mp: 314-316 °C; IR (CHCI3, cm ^"1 ): D _max 3420, 1620, 1600, 1580, 1550, 1298, 1250, 1033; 1H NMR (200 MHz, CF ₃ C0 ₂ D): 5 .12 (s, 1H), 7.83 (s, 1H), 7.40 (s, 1H), 6.38 (s, 2H), 4.71 (q, J = 7.2 Hz, 2H), 1.69 (t, J = 7.2 Hz, 3H); ^l3 C NMR (50 MHz, CF ₃ C0 ₂ D): δ 169.8, 158.6, 151.0, 146.3, 139.7, 123.3, 1 17.7, 1 12.0, 105.1, 101.7, 96.2, 53.5, 13.9; HRMS (ESI): calc. for [(Ci ₃ H _n N0 ₅ )H] (M+H) 262.0715, found 261.0711.

ADVANTAGES OF THE PRESENT INVENTION

a. Simple, one pot process,

b. Cheaper process,

c. High yielding process,

d. Recyclability of catalyst which is very important in the industrial purposes, The disclosed process is further used for the synthesis of oxolinic acid which is a quinolone antibiotic and antibacterial used in treatment of urinary tract infections and psoriasis.