Method for the synthesis of quinoline derivatives

Abstract

This invention relates to novel intermediates and processes for preparing pharmaceutically active quinoline compounds, including (−)-(S)—N-(α-ethylbenzyl)-3-hydroxy-2-phenylquinoline-4-carboxamide.

1 . A method for preparing a compound of formula (I):  
     
       
         
         
             
             
         
       
     
     or a pharmaceutically acceptable salt form thereof, wherein: 
 Ar is an optionally substituted phenyl group, or a naphthyl or C 5-7  cycloalkdienyl group, or an optionally substituted single or fused ring heterocyclic group, having aromatic character, containing from 5 to 12 ring atoms and comprising up to four hetero-atoms in the or each ring selected from S, O, N;  
 R is linear or branched C 1-8  alkyl, C 3-7  cycloalkyl, C 4-7  cycloalkylalkyl, an optionally substituted phenyl group or a phenyl C 1-6  alkyl group, an optionally substituted five-membered heteroaromatic ring comprising up to four heteroatom selected from O and N, hydroxy C 1-6  alkyl, di C 1-6  alkylaminoalkyl, C 1-6  acylaminoalkyl, C 1-6  alkoxyalkyl, C 1-6  alkylcarbonyl, carboxy, C 1-6  alkoxycarbonyl, C 1-6  alkoxycarbonyl C 1-6  alkyl, aminocarbonyl, C 1-6  alkylaminocarbonyl, di C 1-6  alkylaminocarbonyl; or is a group —(CH 2 ) p — when cyclized onto Ar, where p is 2 or 3;  
 R 1 and R 2 , which may be the same or different, are independently hydrogen or C 1-6  linear or branched alkyl, or together form a —(CH 2 ) n — group in which n represents 3, 4, or 5; or R 1  together with R forms a group —(CH 2 ) q —, in which q is 2, 3, 4 or 5;  
 R 3  and R 4 , which may be the same or different, are independently hydrogen, C 1-6  linear or branched alkyl, C 1-6  alkenyl, aryl, C 1-6  alkoxy, hydroxy, halogen, nitro, cyano, carboxy, carboxamido, sulphonamido, trifluoromethyl, amino, mono- and di-C 1-6  alkylamino, —O(CH 2 ) r —NT 2 , in which r is 2, 3, or 4 and T is C 1-6  alkyl or it forms a heterocyclic group  
                     
 in which V and V 1  are hydrogen and u is 0, 1 or 2;  
 —O(CH 2 ) s —OW 2  in which s is 2, 3, or 4 and W is C 1-6  alkyl; hydroxyalkyl, mono- or di-alkylaminoalkyl, acylamino, alkylsulphonylamino, aminoacylamino, mono- or di-alkylaminoacylamino; with up to four R 3  substituents being present in the quinoline nucleus;  
 or R 4  is a group —(CH 2 ) t — when cyclized onto R 5  as aryl, in which t is 1, 2, or 3; and  
 R 5  is branched or linear C 1-6  alkyl, C 3-7  cycloalkyl, C 4 - 7  cycloalkylalkyl, optionally substituted aryl, wherein the optional substituent is one of hydroxy, halogen, C 1-6  alkoxy or C 1-6  alkyl, or an optionally substituted single or fused ring heterocyclic group, having aromatic character, containing from 5 to 12 ring atoms and comprising up to four hetero-atoms in the or each ring selected from S, O, N; comprising:  
 1) adding a compound of formula (III):  
                     
 to base in a suitable solvent, to form a first reaction mixture, adding to the first reaction mixture a compound of formula (II):  
                     
 to form a second reaction mixture, and heating the second reaction mixture to form a compound of formula (IV):  
                     
 2) isolating the compound of formula (IV) and then reacting the compound of formula (IV), in a suitable solvent, with a base to form a third reaction mixture, cooling the third reaction mixture, and adding thionyl chloride to form a fourth reaction mixture;  
 3) adding a compound of formula (V):  
                     
 to the fourth reaction mixture to form a fifth reaction mixture;  
 4) heating the fifth reaction mixture; and  
 5) optionally converting the compound of formula (I) to a pharmaceutically acceptable salt thereof, wherein Ar, R, R 1 , R 2 , R 3 , R 4 , and R 5  as used in a compound of formulae (II) through (VI) are as defined for a compound of formula (I).  
 
   
   
       2 . The method as claimed in  claim 1 , wherein for the compound of formula (I): 
 Ar is phenyl, optionally substituted by C 1-6  alkyl or halogen; thienyl or a C 5-7  cycloalkdienyl group;    R is C 1-6  alkyl, C 1-6  alkoxycarbonyl, C 1-6  alkylcarbonyl, hydroxy C 1-6  alkyl;    R 1  and R 2  are each hydrogen or C 1-6  alkyl;    R 3  is hydrogen, hydroxy, halogen, C 1-6  alkoxy, C 1-6  alkyl;    R 4  is hydrogen, C 1-6  alkyl, C 1-6  alkoxy, hydroxy, amino, halogen, aminoalkoxy, mono- or di-alkylaminoalkoxy, mono- or di-alkylaminoalkyl, phthaloylalkoxy, mono- or di-alkylaminoacylamino and acylamino; and    R 5  is phenyl, thienyl, furyl, pyrryl and thiazolyl.    
   
   
       3 . The method as claimed in  claim 2 , wherein for the compound of formula (I): 
 Ar is phenyl;    R is ethyl;    R 1  and R 2  are each hydrogen;    R 3  is hydrogen;    R 4  is hydroxy; and    R 5  is phenyl.    
   
   
       4 . A method for preparing (−)-(S)—N-(α-ethylbenzyl)-3-hydroxy-2-phenylquinoline-4-carboxamide comprising: 
 1) reacting 3-hydroxy-2-phenylquinoline-4-carboxylic acid, in a suitable solvent, with triethyl amine to form a first reaction mixture, cooling the first reaction mixture, and adding thionyl chloride to form a second reaction mixture comprising 6,14,22,30-Tetraphenyl-[1,5,9,13]tetraoxahexadecino[2,3-c:6,7-c′:10,11-c″:14,15-c′″]tetraquinoline-8,16,24,32-tetrone and Ethyl 3-acetoxy-2-phenylquinoline-4-carboxylate;    2) adding (S)-1-phenyl propylamine to the second reaction mixture to form a third reaction mixture comprising (−)-(S)—N-(α-ethylbenzyl)-3-hydroxy-2-phenylquinoline-4-carboxamide and (S)-2-Phenyl-4-[[(1-phenylpropyl)amino]carbonyl]-3-quinolinyl-3-hydroxy-2-phenyl-4-quinoline-carboxylate;    3) heating the third reaction mixture; and    4) optionally converting (−)-(S)—N-((α-ethylbenzyl)-3-hydroxy-2-phenylquinoline-4-carboxamide to a pharmaceutically acceptable salt.    
   
   
       5 . A compound of formula (VII):  
     
       
         
         
             
             
         
       
     
     wherein: 
 Ar is an optionally substituted phenyl group, or a naphthyl or C 5-7  cycloalkdienyl group, or an optionally substituted single or fused ring heterocyclic group, having aromatic character, containing from 5 to 12 ring atoms and comprising up to four hetero-atoms in the or each ring selected from S, O, N; and  
 R 3  is hydrogen, C 1-6  linear or branched alkyl, C 1-6  alkenyl, aryl, C 1-6  alkoxy, hydroxy, halogen, nitro, cyano, carboxy, carboxamido, sulphonamido, trifluoromethyl, amino, mono- and di-C 1-6  alkylamino, —O(CH 2 ) r —NT 2 ,in which r is 2, 3, or 4 and T is C 1-6  alkyl or it forms a heterocyclic group  
                     
 in which V and V 1  are hydrogen and u is 0, 1 or 2;  
 —O(CH 2 ) s —OW 2  in which s is 2, 3, or 4 and W is C 1-6  alkyl; hydroxyalkyl, mono- or di-alkylaminoalkyl, acylamino, alkylsulphonylamino, aminoacylamino, mono- or di-alkylaminoacylamino; with up to four R 3  substituents being present in the quinoline nucleus; and  
 R′ 4  is OH or OAc.  
 
   
   
       6 . The compound of formula (VII) according to  claim 5 , which is  
     
       
         
         
             
             
         
       
     
   
   
       7 . A compound of formula (VIII):  
     
       
         
         
             
             
         
       
     
     wherein: 
 Ar and R 3  are as defined for a compound of formula (I) as claimed in  claim 1;  and  
 n is 1 or 3.  
 
   
   
       8 . The method as claimed in  claim 1 , wherein the compound of formula (I) is (−)-(S)—N-(α-ethylbenzyl)-3-hydroxy-2-phenylquinoline-4-carboxamide.  
   
   
       9 . A compound which is (−)-(S)—N-(α-ethylbenzyl)-3-hydroxy-2-phenylquinoline-4-carboxamide, hydrochloride salt.  
   
   
       10 . A method for preparing a compound of formula (Ia):  
     
       
         
         
             
             
         
       
     
     wherein: 
 Ar is an optionally substituted phenyl group, or a naphthyl or C 5-7  cycloalkdienyl group, or an optionally substituted single or fused ring heterocyclic group, having aromatic character, containing from 5 to 12 ring atoms and comprising up to four hetero-atoms in the or each ring selected from S, O, N;  
 R is linear or branched C 1-8  alkyl, C 3-7  cycloalkyl, C 4-7  cycloalkylalkyl, an optionally substituted phenyl group or a phenyl C 1-6  alkyl group, an optionally substituted five-membered heteroaromatic ring comprising up to four heteroatom selected from O and N, hydroxy C 1-6  alkyl, di C 1-6  alkylaminoalkyl, C 1-6  acylaminoalkyl, C 1-6  alkylcarbonyl, carboxy, C 1-6  alkoxycarbonyl, C 1-6  alkoxycarbonyl C 1-6  alkyl, aminocarbonyl, C 1-6  alkylaminocarbonyl, di C 1-6  alkynylaminocarbonyl; or is a group —(CH 2 ) p — when cyclized onto Ar, where p is 2 or 3;  
 R 2  is hydrogen or C 1-6  linear or branched alkyl; and  
 R 3  and R 4 , which may be the same or different, are independently hydrogen, C 1-6  linear or branched alkyl, C 1-6  alkenyl, aryl, C 1-6  alkoxy, hydroxy, halogen, nitro, cyano, carboxy, carboxamido, sulphonamido, trifluoromethyl, amino, mono- and di-C 1-6  alkylamino, —O(CH 2 ) r —NT 2 , in which r is 2, 3, or 4 and T is C 1-6  alkyl or it forms a heterocyclic group  
                     
 in which V and V 1  are hydrogen and u is 0, 1 or 2;  
 —O(CH 2 ) s —OW 2  in which s is 2, 3, or 4 and W is C 1-6  alkyl; hydroxyalkyl, mono- or di-alkylaminoalkyl, acylamino, alkylsulphonylamino, aminoacylamino, mono- or di-alkylaminoacylamino; with up to four R 3  substituents being present in the quinoline nucleus;  
 comprising:  
 1) adding a compound of and formula (III):  
                     
 to base in a suitable solvent, to form a first reaction mixture, adding to the first reaction mixture a compound of formula (IIa):  
                     
 to form a second reaction mixture, and heating the second reaction mixture to form a compound of formula (IVa):  
                     
 2) isolating the compound of formula (IVa) and then reacting the compound of formula (IVa), in a suitable solvent, with a base to form a third reaction mixture, cooling the third reaction mixture, and adding a carbonyl-activating agent to form a fourth reaction mixture;  
 3) adding a compound of formula (Va):  
                     
 to the fourth reaction mixture to form a fifth reaction mixture;  
 4) heating the fifth reaction mixture; and  
 5) optionally converting the compound of formula (I) to a pharmaceutically acceptable salt thereof, wherein Ar, R, R 1 , R 2 , R 3 , R 4 , and R 5  as used in a compound of formulae (IIa), and (IVa) through (VIa) are as defined for a compound of formula (Ia).