Process for producing phenyl-substituted heterocyclic derivative through coupling using transition metal catalyst
View Patent ↗A process for efficiently producing, through few steps either a xanthine oxidase inhibitor, which is a therapeutic agent for hyperuricemia, or an intermediate therefore. The process is a novel coupling process which comprises subjecting a compound represented by formula (1) to coupling reaction with a compound represented by formula (2) in the presence of a transition metal compound to thereby obtain a compound represented by formula (3).
1. A process comprising reacting a compound represented by the following formula (1):
(In the formula (1), R 1 represents a hydrogen atom or halogen atom; R 2 represents a hydrogen atom, cyano group, nitro group, halogen atom, formyl group, or halomethyl group; A represents a hydrogen atom, C 1 to C 8 alkyl group, C 3 to C 6 cycloalkyl group, phenyl group, fluorine atom (only when X is a bond), or protecting group for a hydroxyl group (only when X is an oxygen atom), wherein A may be substituted by 1 to 3 substituents, such substituent representing a group selected from the group consisting of a halogen atom, C 1 to C 4 alkyl group, C 1 to C 4 alkoxy group, C 1 to C 4 alkylthio group, C 3 to C 6 cycloalkyl group, phenyl group, phenoxy group, and pyridyl group; X represents a bond (only when A is a phenyl group or fluorine atom) or oxygen atom; and Y represents a leaving group)
and a compound represented by the following formula (2):
(In the formula (2), H represents a hydrogen atom;
R 3 represents COOR 3a or COR 3b ; R 3a represents a hydrogen atom, C 1 to C 4 alkyl group, or ester-type protecting group for a carboxyl group; R 3b represents a amide-type protecting group for a carboxyl group, the protecting group forming an amide with a neighboring carbonyl group; R 4 represents a hydrogen atom, halogen atom, or C 1 to C 4 alkyl group);
in the presence of a transition metal compound selected from the group consisting of zero-valent palladium and a salt of mono- or di-valent palladium to produce a phenyl-substituted heterocyclic derivative represented by the following formula (3):
(in the formula (3), A, X, R 1 , and R 2 are the same as defined in the formula (1); and R 3 and R 4 are the same as defined in the formula (2)).
2. The production process according to claim 1 , wherein A is a C 1 to C 5 alkyl group.
3. The production process according to claim 1 , wherein A is an isobutyl group.
4. The production process according to claim 1 , wherein X is an oxygen atom.
5. The production process according to claim 1 , wherein R 1 is a hydrogen atom.
6. The production process according to claim 1 , wherein R 2 is a cyano group.
7. The production process according to claim 1 , wherein Y represents a halogen atom, —OCO 2 —(C 1 to C 4 alkyl group), —OCO 2 -(phenyl group), —OSO 2 —(C 1 to C 4 alkyl group), —OSO 2 -(phenyl group), or a diazonium group wherein, in Y, the C 1 to C 4 alkyl group may be substituted with 1 to 3 halogen atoms and the phenyl group may be substituted with 1 to 3 halogen atoms or C 1 to C 4 alkyl groups.
8. The production process according to claim 1 , wherein R 4 is a methyl group.
9. The production process according to claim 1 , wherein the transition metal compound is palladium (II) acetate (Pd(OAc) 2 ), palladium (II) propionate (Pd(O(C═O)CH 2 CH 3 ) 2 ), palladium (II) 2-methylpropanoate (Pd(O(C═O)CH(CH 3 ) 2 ) 2 , palladium pivalate (Pd(OPiv) 2 ), palladium (II) chloride (PdCl 2 ), palladium (I) bromide (Pd 2 Br 2 ), or palladium (II) hydroxide (Pd(OH) 2 ).
10. The production process according to claim 1 , wherein the transition metal compound is palladium (II) acetate (Pd(OAc) 2 ), palladium (II) propionate (Pd(O(C═O)CH 2 CH 3 ) 2 ), palladium (II) 2-methylpropanoate (Pd(O(C═O)CH(CH 3 ) 2 ) 2 , or palladium pivalate (Pd(OPiv) 2 ).
11. The production process according to claim 1 , wherein a ligand capable of coordinating to the transition metal compound is additionally present during the course of the reaction.
12. The production process according to claim 11 , wherein the ligand is a phosphine-type ligand.
13. The production process according to claim 12 , wherein the phosphine-type ligand is tri(tert-butyl)phosphine, di(tert-butyl)methylphosphine, tert-butyldicyclohexylphosphine, di(tert-butyl)cyclohexylphosphine, tri(cyclohexyl)phosphine, 2-dicyclohexylphosphino-2′,6′-diisopropoxy-1,1′-biphenyl, 2-dicyclohexylphosphino-2′,4′,6′-triisopropyl-1,1′-biphenyl, or a salt thereof.
14. The production process according to claim 1 , wherein a base is additionally present during the course of the reaction.
15. The production process according to claim 14 , wherein the base is potassium carbonate, potassium bicarbonate, cesium carbonate, or tetra-n-butylammonium fluoride.
16. The production process according to claim 1 , wherein a silver salt is additionally present during the course of the reaction.
17. The production process according to claim 16 , wherein the silver salt is silver carbonate.
18. The production process according to claim 1 , wherein a C 1 to C 12 carboxylic acid or salt thereof is additionally present during the course of the reaction.
19. The production process according to claim 18 , wherein the carboxylic acid or salt thereof is 2-methylpropanoic acid, pivalic acid, or a salt thereof.