Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Patent
1996-02-23
1997-01-28
Springer, David B.
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
548101, C07D40504
Patent
active
055979297
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/JP95/01261 filed Jun. 23, 1995.
1. Field of Invention
The present invention relates to production processes of 2-(tetrazol-5-yl)-4-oxo-4H-benzopyrans which are useful as pharmaceuticals or intermediates thereof.
2. Prior Art
2-(Tetrazol-5-yl)-4-oxo-4H-benzopyrans of general formula (1): ##STR4## wherein R.sup.1 and R.sup.2 are the same or different and are a hydrogen atom, a hydroxy group, a halogen atom, a C.sub.1 -C.sub.20 alkyl group, a C.sub.1 -C.sub.20 alkoxy group, an R.sup.3 CONH group or a nitro group, in which R.sup.3 is a C.sub.1 -C.sub.20 alkyl group optionally substituted with an aryl group, or a phenyl group optionally substituted with R.sup.4 ; R.sup.4 is a C.sub.1 -C.sub.20 alkyl group optionally substituted with an aryl group, or a C.sub.1 -C.sub.20 alkoxy group optionally substituted with an aryl group; R.sup.5 is a hydrogen atom, an alkyl or alkenyl group optionally substituted with an electron withdrawing group, an alkyl group substituted with 1 to 3 aryl groups, an alkoxycarbonyl group optionally substituted with an aryl group, an aryloxycarbonyl group, an alkoxymethyl group, a trialkyl tin group, a triaryl tin group or a trialkylsilyl group, in which the term "aryl group" or "aryl" means a phenyl group optionally substituted with a group selected from an alkyl group, an alkoxy group or a halogen atom, are compounds which are useful, for example, as antiasthmatics or intermediates thereof.
As a production process of 2-(tetrazol-5-yl)-4-oxo-4H-benzopyran (1), there has been known the following process which is disclosed, for example, in Journal of Medicinal Chemistry, 1972, 15, p.865. ##STR5##
As a production process of 2-(tetrazol-5-yl)-4-oxo-4H-benzopyran (1) with a substituent introduced on the tetrazole ring, the following process is disclosed, for example, in publications GB-A1362782 and GB-A1356379. ##STR6##
However, this process requires an additional reaction in the following step to obtain the above starting material compound from hydroxyacetophenone. ##STR7##
Therefore, these processes are complicated because of their involving many reaction steps, and they cannot attain satisfactory yield.
As a production process of a compound corresponding to 2-(tetrazol-5-yl)-4-oxo-4H-benzopyran (1) wherein substituent R.sup.5 is a hydrogen atom, there is disclosed the following process, for example, in publication WO94/12492. ##STR8##
In the process described therein, tetrahydrofuran or N,N-dimethylformamide is used as the reaction solvent. When this process is applied to the production on an industrial scale, the use of such a solvent is not preferred from the viewpoint of its cost, safety, and difficulty in solvent recovery.
OBJECTS OF THE INVENTION
An object of the present invention is to provide a process for producing 2-(tetrazol-5-yl)-4-oxo-4H-benzopyrans (1) in an industrially favorable manner, which are useful as drug substances or pharmaceutical intermediates. This and other objects and excellent advantages will be understood from the following description.
SUMMARY OF THE INVENTION
The present inventors have intensively studied to solve the above problems of the prior art. As a result, they have found that the reaction can be smoothly effected even in an industrially favorable solvent by using, as a tetrazole compound, those having a substituent on the tetrazole ring and further that 2-(tetrazol-5-yl)-4-oxo-4H-benzopyrans can be produced in an industrially favorable manner, and they have made further studies, thereby completing the present invention.
Thus, the present invention provides a process for producing 2-(tetrazol-5-yl)-4-oxo-4H-benzopyran (1), which comprises reacting a hydroxyacetophenone of general formula (2): ##STR9## wherein R.sup.1 and R.sup.2 are as defined above, with a tetrazole compound of general formula (3): ##STR10## wherein R.sup.5' is R.sup.5 which is not a hydrogen atom, R.sup.6 is a lower alkyl group optionally substituted with a halogen atom, and R.sup.5 is as defined above, in the presence of a base in a solvent com
Higashii Takayuki
Ushio Hideki
Springer David B.
Sumitomo Chemical Co,. Ltd.
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