Organic compounds -- part of the class 532-570 series – Organic compounds – Amino nitrogen containing
Patent
1999-11-29
2000-09-19
Barts, Samuel
Organic compounds -- part of the class 532-570 series
Organic compounds
Amino nitrogen containing
C07C20900
Patent
active
061214922
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method for the preparation of aromatic compounds containing a 2-methoxyaminophenyl group, more particularly 2-trifluoromethoxyaniline.
2-Trifluoromethoxyaniline is an intermediate in the synthesis of many pharmaceutical and agrochemical products.
Various synthetic routes have been proposed.
Several processes using 2-nitrotrifluoro-methoxyphenyl and consisting in reducing it by catalytic hydrogenation or by SnCl.sub.2 in acidic medium are thus known. (ZHUR.OBSHCHEI.KHIM. (31) 1961, p. 915-924, (CA C55)23408); J. Org. Chem. (29), 1964, p. 1-11).
Another process described in ZHUR.OBSHCHEI.KHIM. (31) 1961, p. 915-924 consists in selectively reducing 4-iodo-2-nitrotrifluoro-methoxyphenyl, obtained from 2-nitrotrifluoro-methoxyaniline, in order to obtain 4-iodotrifluoro-methoxyaniline and in hydrogenating this product over Raney nickel.
The present invention provides a novel method for the preparation of aromatic compounds containing a 2-trifluoromethoxyaminophenyl group from aromatic compounds containing a 2-methoxyaminophenyl group.
More precisely, the invention relates to a method for the preparation of a compound of formula I ##STR3## in which R.sub.1 and R.sub.2, which may be identical or different, represent a hydrogen atom, a C.sub.1 -C.sub.6 alkyl group, or R.sub.1 and R.sub.2, taken together with the carbon atoms to which they are attached, represent a C.sub.6 -C.sub.10 aryl group; comprising the following steps: ##STR4## in which R.sub.1, R.sub.2 and R.sub.3 represent the above values or R.sub.1 represents a hydrogen atom or a C.sub.1 -C.sub.6 alkyl group and at least one from among R.sub.2 and R.sub.3 represents a chlorine atom, the other being a hydrogen atom or a C.sub.1 -C.sub.6 alkyl group, are attached, represent a C.sub.6 -C.sub.10 aryl ring, and R.sub.3 represents a hydrogen atom, a C.sub.1 -C.sub.6 alkyl group or a chlorine atom, ##STR5## in which R.sub.1, R.sub.2 and R.sub.3 are as defined above b) reducing the compound of formula III in order to form the compound of formula IV: ##STR6## in which R.sub.1, R.sub.2 and R.sub.3 are as defined above c) subjecting the compound obtained in b) to a dehydrochlorination in order to obtain the compound of formula I; and
Step a) is advantageously carried out by reacting the compound of general formula II with nitric acid in sulphuric acid medium, in a protic solvent, for example acetic acid, or an aprotic solvent, advantageously a chlorinated solvent, for example dichloromethane, or without a solvent.
The reaction temperature is within the range from 0 to 60.degree. C., the reaction preferably being carried out between 20 and 40.degree. C.
After step a), where appropriate, the positional enantiomers obtained are separated in order to isolate the 2-nitrotrifluoromethoxyphenyl compound.
Step b) is advantageously a catalytic hydrogenation in the presence of Raney nickel in a solvent such as an alcohol or acetic acid.
As a variant, the nitro function can be reduced to amino according to a Bechamp reaction in the presence of Fe, in hydrochloric acid medium in acetic acid or in water, as solvent.
Another variant consists in reducing the compound of the preceding step with SnCl.sub.2 in hydrochloric acid medium in ethanol, by heating the reaction medium at reflux for a period ranging from one to several hours.
Step c) can be carried out by hydrogenation of the compound of step b) in the presence of Raney nickel, using an alcohol or acetic acid as solvent.
Steps b) and c) can be carried out simultaneously.
Step a) is optional but preferred, any other method for obtaining the compound of formula II being acceptable.
The starting materials are known compounds which can be prepared simply.
For example, 4-chlorotrifluoromethoxybenzene can be prepared, for example, from p-chlorophenol as described in ZHUR.OBSHCHEI.KHIM. (31) 1961, p. 915-924, (CA C55) 23408); J. Org. Chem. (29), 1964, p.1-11.
As compounds of formula II, those compounds are preferred in which R.sub.1, R.sub.2 and R.sub.3 represent hydrogen or R.sub.2 and R.sub.3 represent c
REFERENCES:
Chemical Abstracts, vol. 55, No. 23, 1961, Columbus, Ohio, US; Abstract No. 23408e, L.M. Yagupolskii: "Synthesis of derivatives of phenyl trifluoromethyl ether", XP002056847 & Zhur. Obshchei Khim, vol. 32, 1961, pp. 915-924., Month Unavailable.
W.A. Sheppard: "Alpha-Fluorinated Ethers. 1-5 1. Aryl Fluoroalkyl Ethers", Journal Of Organic Chemistry., vol. 29, No. 1, 1964, Easton, US, pp. 1-11, XP002056846, p. 9-P. 10., Month Unavailable.
Barts Samuel
Rhodia Chimie
LandOfFree
Method for preparing 2-trifluoro-methoxy-aniline does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for preparing 2-trifluoro-methoxy-aniline, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for preparing 2-trifluoro-methoxy-aniline will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1074853