Methods for the preparation of 4-hydroxy benzothiophene

Details Methods for the preparation of 4-hydroxy benzothiophene Methods for the preparation of 4-hydroxy benzothiophene

2001-11-08

2002-11-19

Solola, T. A. (Department: 1626)

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

C549S080000, C549S079000

Reexamination Certificate

active

06482958

ABSTRACT:

BACKGROUND OF THE INVENTION
Methods for the preparation of 4-hydroxybenzothiophene have been described by Iwasaki et al. (1991) J. Org. Chem. 1991. 56, 1922. Here a cyclocarbonylation of a primary allylacetate is performed in presence of a high catalyst loading. Further, this process is characterized by at least five process steps which in part require extreme reaction conditions. Therefore, a simpler more efficient process utilizing less process steps has been long desired.
SUMMARY OF INVENTION
The present invention is concerned with a novel process for the preparation of benzothiophene derivatives, especially with the preparation of 4-hydroxybenzothiophene. 4-Hydroxybenzothiophene is a building block for pharmaceutically active compounds, e.g. 5-[4-[2-(5-methyl-2-phenyl-4-oxazolyl)ethoxy]-7-benzothiophenylmethyl]-2,4-thiazolidinedione. This compound is known in the art and is described for example in International Patent Application WO 94/27995. It is especially useful for prophylaxis and treatment of diabetes mellitus type I and II.
Surprisingly it has been found that using the process according to the present invention 4-hydroxybenzothiophene can be prepared with less process steps under moderate conditions with an outstanding yield.


REFERENCES:
patent: 5380861 (1995-01-01), Scalone et al.
patent: 6194446 (2001-02-01), Dominianni et al.
patent: WO 94/27995 (1994-12-01), None
patent: WO 98/42704 (1998-10-01), None
Iwasaki et al., J. Org. Chem. 56, pp. 1922-1927 (1991).
Matsuzaka et al., Org. Chem. 53, pp. 3832-3838 (1988).
Practical Organic Chemistry, A. I. Vogel, Longmans Ed., pp. 390-393 (1967).
Houben-Weyl, “Methoden der organischen Chemie”, vol. E1, pp. 106-182, Georg Thieme Verlag Stuttgart (1982).
Aspects Homog. Catal., 4, pp. 145-202 (1981).

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