NOVEL METHOD FOR SYNTHESIS OF 1,4-MORPHOLINE-2,5-DIONES

1 . A process for the preparation of 1,4-morpholine-2,5-diones of formula (I)

in which R, R 1 , R 2 , R 3 and R 4 represent, independently, the hydrogen atom; halo; (C 2 -C 6 )alkenyl; (C 3 -C 7 )cycloalkyl; cyclohexenyl; a radical of formula —(CH 2 ) m —V—W;

V represents a covalent bond, the oxygen or sulphur atom, the —C(O)—O— or —NR N — radical;

R N represents the hydrogen atom; a (C 1 -C 18 )alkyl radical optionally substituted by one or more identical or different substituents chosen from halo and cyano; the aryl or aralkyl radical, the aryl and aralkyl radicals being optionally substituted by one or more identical or different substituents chosen from: —(CH 2 ) n —Y-Z, halo, nitro and cyano;

W represents the hydrogen atom; a (C 1 -C 18 )alkyl radical optionally substituted by one or more identical or different substituents chosen from halo, benzoyl, benzyloxy and cyano;

(C 2 -C 6 )alkenyl; (C 2 -C 6 )alkynyl; —SiR 5 R 6 R 7 ; aryl or aralkyl, the benzoyl, benzyloxy, aryl and aralkyl radicals being optionally substituted by one or more identical or different substituents chosen from: —(CH 2 ), —Y-Z, halo, nitro and cyano;

R 5 , R 6 and R 7 represent, independently, a (C 1 -C 6 )alkyl or aryl radical;

Y represents —O—, —S— or a covalent bond;

Z represents the hydrogen atom or a (C 1 -C 6 )alkyl radical optionally substituted by one or more identical or different halo radicals; or aralkyl;

m and n represent independently an integer from 0 to 4;

comprising oxidizing the ketone function of a cyclic compound of formula (II)

in which R, R 1 , R 2 , R 3 and R 4 are as defined above; and

optionally treating the compound of formula (Ia)

with a cleavage agent in order to obtain the compound of formula (I) in which R 1 represents the hydrogen atom, such that, with respect to the compound of formula (Ia), R, R 2 , R 3 and R 4 are as defined above and R 1a represents a labile group of formula —(CH 2 ) m —V—W as defined above with m which is equal to zero and V which represents the —C(O)—O— radical.

2 . The process according to claim 1 , for the preparation of the compound of formula (I) in which R 1 and R 2 represent, independently, halo; (C 2 -C 6 )alkenyl; (C 3 -C 7 )cycloalkyl; cyclohexenyl; or a radical of formula —(CH 2 ) m —V—W.

3 . The process according to claim 1 , for the preparation of the compound of formula (I) in which R 1 represents the hydrogen atom,

comprising oxidizing the ketone function of a cyclic compound of formula (IIa)

in which R, R 2 , R 3 and R 4 are as defined in claim 1 , and R 1a represents a labile group of formula —(CH 2 ) m —V—W as defined in claim 1 with m which is equal to zero and V which represents the —C(O)—O— radical,

treating the compound (Ia) thus obtained

with a cleavage agent in order to produce the compound of formula (I) in which R 1 represents hydrogen, such that, with respect to the compound of formula (Ia), R, R 1a , R 2 , R 3 and R 4 are as defined above.

4 . The process according to claim 1 , wherein the labile group that R 1a represents is of formula —(CH 2 ) m —V—W with m which is equal to zero, V represents the —C(O)—O— radical, and

W represents a (C 1 -C 18 )alkyl radical substituted by halo, benzoyl or benzyloxy; (C 2 -C 6 )alkenyl; (C 2 -C 6 )alkynyl; —SiR 5 R 6 R 7 ; aryl or aralkyl, the benzoyl, benzyloxy, aryl and aralkyl radicals being optionally substituted by one or more identical or different substituents chosen from: —(CH 2 ) n —Y-Z, halo, nitro and cyano;

Y represents —O— or a covalent bond; and

R 5 , R 6 and R 7 represent, independently, a (C 1 -C 6 )alkyl or aryl radical.

5 . The process according to claim 1 , wherein the process is carried out in the presence of an oxidizing agent.

6 . The process according to claim 5 , wherein the oxidizing agent is used in the presence of a catalyst.

7 . The process according to claim 5 , wherein the oxidizing agent is a peracid or a peroxide.

8 . The process according to claim 5 , wherein the oxidizing agent is a peracid.

9 . The process according to claim 8 , wherein the oxidizing agent is used in the presence of a Lewis acid or a strong acid.

10 . The process according to claim 9 , wherein the oxidizing agent is used in the presence of a strong acid chosen from the sulphonic acids.

11 . The process according to claim 8 , wherein the oxidizing agent is used in the presence of a base.

12 . The process according to claim 11 , wherein the oxidizing agent is used in the presence of an inorganic base.

13 . The process according to claim 8 , wherein the oxidizing agent is metachloroperbenzoic acid.

14 . The process according to claim 13 , wherein the oxidizing agent is used in the presence of trifluoromethanesulphonic acid.

15 . The process according to claim 13 , wherein the oxidizing agent is used in the presence of a hydrogen carbonate or carbonate salt.

16 . The process according to claim 5 , wherein the oxidizing agent is a peroxide.

17 . The process according to claim 1 , wherein R represents the hydrogen atom or a radical of formula —(CH 2 ) m —V—W with V which represents a covalent bond or the —C(O)—O— radical and W an optionally substituted aralkyl radical; R 1 , R 2 , R 3 and R 4 represent, independently, the hydrogen atom or a radical of formula —(CH 2 ) m —V—W with V which represents a covalent bond and W a (C 1 -C 6 )alkyl radical.

18 . The process according to claim 1 , wherein R represents the hydrogen atom or an optionally substituted aralkyl radical.

19 . The process according to claim 1 , wherein the term aryl of the aryl and aralkyl radicals is the phenyl radical and m is equal to zero or one.

20 . The process according to claim 1 , wherein R represents the hydrogen atom or the benzyl radical, R 1 and R 2 , represent, independently, the hydrogen atom or the methyl or ethyl radical, and R 3 and R 4 represent, independently, the hydrogen atom or a methyl radical.

21 . The process according to claim 1 , wherein said process is carried out at a temperature between 20 and 80° C. in the presence of 1 to 3 molar equivalents of oxidizing agent with respect to the substrate.

22 . The process according to claim 1 , wherein said process is carried out in an organic solvent, at a substrate concentration between 0.01 M and 2 M.

23 . A compound according to formula (Ib)

in which

R b represents an arylalkyl radical;

R 1b , R 3b and R 4b represent, independently, the hydrogen atom; halo; (C 2 -C 6 )alkenyl; (C 3 -C 7 )cycloalkyl; cyclohexenyl; or a radical of formula —(CH 2 ) m —V—W;

R 2b represents halo; (C 2 -C 6 )alkenyl; (C 3 -C 7 )cycloalkyl; cyclohexenyl; a radical of formula —(CH 2 ) m —V—W;

V represents a covalent bond, the oxygen or sulphur atom, the —C(O)—O— or —NR N — radical;

R N represents the hydrogen atom; a (C 1 -C 18 )alkyl radical optionally substituted by one or more identical or different substituents chosen from halo and cyano; the aryl or aralkyl radical, the aryl and aralkyl radicals being optionally substituted by one or more identical or different substituents chosen from: —(CH 2 ) n —Y-Z, halo, nitro and cyano;

W represents the hydrogen atom, a (C 1 -C 18 )alkyl radical optionally substituted by one or more identical or different substituents chosen from halo, benzoyl, benzyloxy and cyano;

(C 2 -C 6 )alkenyl; (C 2 -C 6 )alkynyl; —SiR 5 R 6 R 7 ; the aryl or aralkyl radical, the benzoyl, benzyloxy, aryl and aralkyl radicals being optionally substituted by one or more identical or different substituents chosen from: —(CH 2 ), —Y-Z, halo, nitro and cyano;

R 5 , R 6 and R 7 represent, independently, a (C 1 -C 6 )alkyl or aryl radical;

Y represents —O—, —S— or a covalent bond;

Z represents the hydrogen atom or a (C 1 -C 6 )alkyl radical optionally substituted by one or more identical or different halo radicals; or aralkyl;

m and n represent independently an integer from 0 to 4;

it being understood that

when W represents the —SiR 5 R 6 R 7 radical, then V represents the —C(O)—O— radical and m is equal to zero; and

when R 1b represents the hydrogen atom and R 2b the radical of formula —(CH 2 ) m —V—W with m which is equal to 1 and V which represents the —C(O)—O— radical, then W does not represent the hydrogen atom.

24 . The compounds according to claim 23 , wherein R 1b represents the hydrogen atom or a radical of formula —(CH 2 ) m —V—W with V which represents a covalent bond or the —C(O)—O— radical; and R 2b represents a radical of formula —(CH 2 ) m —V—W with V which represents a covalent bond or the —C(O)—O— radical.

25 . The compounds according to claim 23 , wherein R 1b represents the hydrogen atom or a (C 1 -C 6 )alkyl radical and R 2b represents a (C 1 -C 6 )alkyl radical.

26 . The compounds according to claim 23 , wherein the term aryl of the aryl and aralkyl radicals is the phenyl radical.

27 . The compound according to claim 23 , wherein R b represents the optionally substituted benzyl radical.

28 . The compounds according to claim 23 , wherein R 3b and R 4b represent, independently, the hydrogen atom or a (C 1 -C 6 )alkyl radical.

29 . The compounds according to claim 23 , wherein R 3b represents the hydrogen atom and R 4b represents the hydrogen atom or a (C 1 -C 6 )alkyl radical.

30 . The compounds according to claim 23 , wherein R 1b represents the hydrogen atom, the methyl, carboxy or benzyloxycarbonyl radical, R 2b a methyl radical, R 3b and R 4b the hydrogen atom, and R b the benzyl radical.

31 . The process according to claim 22 , wherein the organic solvent is a chlorinated organic solvent.