Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Patent
1997-03-28
1998-03-03
Morris, Patricia L.
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C07D24912
Patent
active
057236240
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a novel process for preparing 5-aryl-2,4-dialkyl-3H-1,2,4-triazole-3-thiones which have previously been shown to have antidepressant activity as disclosed in U.S. Pat. No. 4,775,688, issued Oct. 4, 1988 and in U.S. Pat. No. 4,912,095, issued Mar. 27, 1990. In addition they have been shown to be useful in the treatment of Wernicke-Korsakoff syndrome as disclosed in U.S. Pat. No. 5,100,906, issued Mar. 31, 1992, and in the treatment of Alzheimer's disease as disclosed in U.S. Patent No. 5,236,942, issued Aug. 17, 1993.
The present invention provides the 5-aryl-2,4-dialkyl-3H-1,2,4-triazole-3-thiones in a single step. The present invention also eliminatese isolation of the intermediate coupled compound and further avoids formation of significant quantities of the generally highly insoluble intermediate compound, while maintaining formation of the desired product in high yield. The 5-aryl-2,4-dialkyl-3H-1,2,4-triazole-3-thiones are isolated directly from the reaction medium by crystallization from a suitable solvent to afford high quality products.
SUMMARY OF THE INVENTION
The present invention provides a novel process for preparing a compound of the formula: ##STR1## wherein R is halogen, C.sub.1-3 alkyl or C.sub.1-3 alkoxy; ##STR2## wherein R.sub.2 and R.sub.3 are defined as above, with a base and an organic solvent; and ##STR3## wherein R and n are defined as above, to the mixture.
DETAILED DESCRIPTION OF THE INVENTION
As used herein the term "C.sub.1-3 alkyl" refers to a saturated straight or branched chain hydrocarbon radical of one to three carbons. Included within the scope of this term are methyl, ethyl, n-propyl and isopropyl. The term "C.sub.1-3 alkoxy" refers to an alkyloxy radical made up of an oxygen radical bearing a saturated or branched chain hydrocarbyl radical of one to three carbon atoms and specifically includes methoxy, ethoxy, propyloxy and isopropyloxy. As used herein the term "halogen" or "halo" refers to a fluorine, chlorine or bromine atom. When n is the integer 1, R may be located at the ortho (position 2), meta (position 3) or para (position 4) position on the phenyl ring. When n is the integer 2, R may be in any of the 2,3-; 2,4-; 2,5-; 2,6-; 3,4-; and 3,5- positions on the phenyl ring.
The process of the present invention is set forth in Scheme I. All the substituents, unless otherwise indicated, are previously defined. The reagents and starting materials are readily available to one of ordinary skill in the art. For example, the general preparation of compounds of structures (1) and (2) are described in U.S. Pat. No. 4,775,688, issued Oct. 4, 1988 and in U.S. Pat. No. 4,912,095, issued Mar. 27, 1990. ##STR4##
In Scheme I, the dialkylthiosemicarbazide (1) is mixed with a suitable base and a suitable organic solvent under an inert atmosphere, such as nitrogen. Examples of a suitable organic solvent are any halocarbon solvent, such as methylene chloride, chloroform, carbon tetrachloride and the like, benzene or a substituted aromatic solvent which contains one or more lower alkyl, alkoxy or halo substituents, such as toluene, o-xylene, m-xylene, p-xylene, chlorobenzene, bromobenzene, anisole and the like. Toluene is the preferred organic solvent. In addition, the reaction can be carried out in the absence of organic solvent. Examples of suitable bases are aqueous bases, such as aqueous sodium hydroxide, aqueous potassium hydroxide, aqueous lithium hydroxide, aqueous sodium bicarbonate, aqueous sodium carbonate and the like, or trialkylamine and pyridine bases, such as triethylamine, tripropylamine, tributylamine, diisopropylethylamine, pyridine and the like. The preferred bases are aqueous sodium hydroxide and triethylamine. The most preferred base is aqueous sodium hydroxide. The aqueous sodium hydroxide may be in a concentration of from 4% to 50% by weight in water. The number of equivalents of base added to the solution can vary from 1.001 to 3.0 equivalents. The preferred number of equivalents added to the solut
REFERENCES:
patent: 4775688 (1988-10-01), Kane et al.
patent: 4912095 (1990-03-01), Kane et al.
patent: 5236942 (1993-08-01), Miller
Kane, John M. et al, J. Med Chem. , vol. 31, (1988) , pp. 1253-1258.
Chemical Abstracts, vol. 109, No. 23, No. 211093q, p. 671 (1988).
Goralski Christian T.
Louks David H.
Puga Yolanda M.
Stolz-Dunn Sandra K.
Lentz Nelsen L.
Merrell Pharmaceuticals Inc
Morris Patricia L.
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