US 4,542,229 AGranted

Process for preparing 2,3-dihydro-2,2-dimethylbenzofuran-7-ol

AssigneeBrichima S.p.A.

InventorsPaolo Maggioni, Francesco Minisci, Mariano Correale

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Abstract

A process is described for preparing 2,3-dihydro-2,2-dimethylbenzofuran-7-ol (I), which is a useful intermediary in the preparation of Carbofuran, a known multi-functional insecticide. The process consists essentially of reacting the pyrocatechol and a methallylhalide in an inert organic solvent in the presence of a solid inorganic base and a suitable catalyst, to obtain o.methallyloxyphenol with high conversion and high selectivity; this product is thermally transposed to o.methallylpyrocatechol, which is finally cyclized to the product (I) by heterogeneous catalysis in the presence of solid acid catalysts. All stages of the process can be carried out in a single reaction medium, without separating intermediate products.

Claims14

Dependent claims

A process for preparing 2,3-dihydro-2,2-dimethylbenzofuran-7-ol of formula ##STR7## which process comprises the steps of:

(a) selective monoetherification of pyrocatechol with a methallyl halide in the presence of an inorganic base in the solid state and a catalyst selected from the group consisting of quaternary ammonium salts, quaternary phosphonium salts and crown ethers;
(b) thermal transposition of the o.methallyloxyphenol obtained in step (a) by heating the solution to a temperature of between 130.degree. and 200.degree. C.;
and (c) cyclisation of the o.methallyl-pyrocatechol obtained in step (b) in the heterogeneous phase by stirring in the presence of an insoluble sulphonic acid resin catalyst at a temperature of between 10.degree. and 150.degree. C., said steps being carried out in a reaction medium consisting of inert organic solvent that remains a liquid at the elevated temperature of the process and in an inert gas atmosphere without separating intermediate products.

Dependencies are inferred from the claim text.