Process for the preparation of oxindoles and ortho-substituted anilines and their use as intermediates for syntheses
View Patent ↗The present invention relates to processes for the preparation of oxindoles and ortho-substituted anilines and their use as intermediates for syntheses. The invention further relates to a process for the preparation of compounds of formula (4): where a mixture of an aniline (compound of formula Q) is reacted with a thioether (compound of formula W): in the presence of a chlorinating agent and an organic solvent at a reaction temperature in the range above −65° C. In a subsequent process, this compound is further reacted in the presence of an acid catalyst to give the indole of formula (7) or the oxindole of formula (8):
1. A process for the preparation of a compound of formula (4),
in which
R1=C1-C6 alkyl, substituted alkyl, aryl or substituted aryl;
R2=H, C1-C6 alkyl or substituted alkyl;
R3=CO—R1 or —CO—X, where X=OR1, SR1, NR2R2′, where R2′ is defined like R2 and may be identical to or different from R2; R2 and R2′ can form a ring; SO(n′)-R1, where n′=may be 0, 1 or 2; —CN; —NO 2 , aryl or heteroaryl;
R4=F, Cl, Br, I, CF 3 , CN, NO 2 , or COX;
where X=OR1, SR1, or NR2R2′, where X=OR1, SR1, NR2R2′, where R2′ is defined like R2 above and may be identical to or different from R2,
n=1-4,
R5=H, C1-C6 alkyl or substituted alkyl,
which comprises reacting a mixture
of an aniline (compound of formula Q):
in which the radicals R4, n and R5 are as defined in formula (4),
with a thioether (compound of formula W):
in which the radicals R1, R2 and R3 are as defined in formula (4),
in the presence of a chlorinating agent and an organic solvent at a reaction temperature in the range between −60 and −10° C., wherein the addition of an additional tertiary amine is dispensed with, to give the compound of formula (4).
2. The process as claimed in claim 1 , wherein the organic solvent comprises an industrially suitable ester solvent.
3. The process as claimed in claim 1 , wherein up to 1 equivalent of the chlorinating agent is added to a mixture of one equivalent of the thioether (compound of formula W) and 2.0 to 5.0 equivalents of the aniline (compound of formula Q).
4. A process for the preparation of a compound of formula (4),
in which
R1=C1-C6 alkyl, substituted alkyl, aryl or substituted aryl;
R2=H, C1-C6 alkyl or substituted alkyl;
R3=—CO—R1 or —CO—X, where X=OR1, SR1, NR2R2′, where R2′ is defined like R2 and may be identical to or different from R2; R2 and R2′ can form a ring; SO(n′)-R1, where n′=may be 0, 1 or 2; —CN; —NO 2 , aryl or heteroaryl;
R4=F, Cl, Br, I, CF 3 , CN, NO 2 , or COX;
where X=OR1, SR1, or NR2R2′, where X=OR1, SR1, NR2R2′, where R2′ is defined like R2 above and may be identical to or different from R2,
n=1-4,
R5=H, C1-C6 alkyl or substituted alkyl,
which comprises reacting a mixture
of an aniline (compound of formula Q):
in which the radicals R4, n and R5 are as defined in formula (4),
with a thioether (compound of formula W):
in which the radicals R1, R2 and R3 are as defined in formula (4),
in the presence of a chlorinating agent and an organic solvent at a reaction temperature in the range between −60 and −10° C. to give the compound of formula (4),
wherein from 1 to 99% by weight of the total amount of the aniline is added separately from, but simultaneously or partially simultaneously with the chlorinating agent.
5. The process as claimed in claim 1 , wherein the reaction temperature is in the range between −50 and −20° C.
6. The process as claimed in claim 1 , wherein 0.7 to 1.0 equivalent of the chlorinating agent is added to a mixture of one equivalent of the thioether (compound of formula W) and 2.0 to 2.5 equivalents of the aniline (compound of formula Q).
7. The process as claimed in claim 1 , wherein from 30 to 70% by weight of the total amount of the aniline is added separately from, but simultaneously or partially simultaneously with the chlorinating agent.
8. The process as claimed in claim 1 , wherein n=1-2.
9. The process as claimed in claim 2 , wherein the organic solvent comprises C1-C6 alkyl acetate or in mixtures thereof, or in a mixture with other solvents.
10. The process as claimed in claim 9 , wherein the organic solvent is selected from the group consisting of methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, 2-methylprop-1-yl acetate, n-butyl acetate, but-2-yl acetate, pentyl acetates, hexyl acetates and cycloalkyl acetates, C1-C6 alkyl and cycloalkyl propionates, C1-C6 alkyl and cycloalkyl n-butyrates, isobutyrates, pentanoates, and hexanoates, and cyclopentanoates, and cyclohexanoates, or in mixtures thereof, or in a mixture with other solvents.
11. The process as claimed in claim 4 , wherein the addition of an additional tertiary amine is dispensed with.
12. The process as claimed in claim 1 , wherein the aniline and the thioether are premixed.
13. The process as claimed in claim 1 , wherein the chlorinating agent is prediluted with the organic solvent and prechilled.