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AssigneeBayer Aktiengesellschaft
InventorsPeter C. Knüppel, Reinhard Lantzsch, Klaus Jelich, Peter Andres, Albrecht Marhold
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A process for the preparation of 3-substituted 4-cyano-pyrrole compounds of the formula (I) in which Ar has the meaning given in the description, by reaction in a 1st stage of bromides (II) Ar—Br (II) with acrylonitrile in the presence of a solvent and a suitable reaction auxiliary to give acrylonitrile derivatives (III) Ar—CH═CH—CN (III) and in a 2nd stage with a phenylsulphonylmethyl isocyanide (IV) Ph—SO2—CH2—CN (IV) in the presence of a solvent and optionally in the presence of a suitable reaction auxiliary, characterised in that the the 1st stage is carried out in the presence of a palladium catalyst and the 2nd stage in the presence of a 1.2- to 1.8-fold molar excess of alkali metal alcoholate or alkali metal hydroxide.
The compound 4-bromo-2,2-difluorobenzodioxole of the formula
Dependencies are inferred from the claim text.
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From the US filing history. Foreign family members aren’t listed.
Ortho- or peri-condensed with carbocyclic rings or ring systems: condensed with one six-membered ring
Heterocyclic compounds
Term ended 20 Mar 2018 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
The invention relates to a new process for the preparation of 3-substituted 4-cyano-pyrrole compounds which may be used as pesticides.
It is known that fungicidally active 3-aryl-4-cyano-pyrrole compounds are obtainable when the correspondingly substituted cinnamonitriles are reacted with p-toluenesulphonylmethyl isocyanide (TOSMIC) in the presence of sodium hydride (compare DE-OS (German Published Specification) 29 27 480 or Tetrahedron Lett. 52, 5337 [1972]). However, this process with yields of approximately 35-45% only gives unsatisfactory results. Also it is disadvantageous that the compounds thus obtainable must be laboriously purified (compare JP 61 30 571). Finally, both the reagents sodium hydride and p-toluenesulphonylmethyl isocyanide (TOSMIC) are not very well suited for technical syntheses, the first because of the high susceptibility to hydrolysis, and the associated fire risk from the gaseous hydrogen liberated during hydrolysis, and the second because of the easy decomposability at elevated temperature (compare EP 174 910).
No better suited for industrial syntheses is the n-butyllithium used as base in an analogous process (compare EP 333 661), which is also very susceptible to hydrolysis and is moreover laborious and expensive to prepare. The use of other bases is described, but with these also only unsatisfactory conversions are achieved (compare e.g. EP 310 558 or EP 206 999).
8.65 g (0.077 mol) of t-potassium butylate are placed in 100 ml of tetrahydrofuran and at −10° C. a mixture of 10 g (0.055 mol) of 2-fluoro-3-chlorocinnamonitrile and 14 g (0.071 mol) of p-toluenesulphonylmethyl isocyanide (TOSMIC) in 200 ml of tetrahydrofuran is added. After stirring for 3 hours at room temperature, the tetrahydrofuran is distilled off in vacuo, the residue is taken up in water, and the resulting precipitate is filtered off with suction and dried.
12.0 g (95% of theory) of 3-cyano-4-(2-fluoro-3-chloro-phenyl)-pyrrole are obtained (content: 95%; determination by HPLC), of melting point 180° C. to 181° C.
1.3 g (0.023 mol) of potassium hydroxide powder is placed in 30 ml of tetrahydrofuran, 9 ml of tris-[2-(2-methoxyethoxy)ethyl]-amine are added and at −10° C. a mixture of 3 g (0.016 mol) of 2-fluoro-3-chlorocinnamonitrile and 4.2 g (0.022 mol) of p-toluenesulphonylmethyl isocyanide (TOSMIC) in 60 ml of tetrahydrofuran is added. After stirring for 3 hours at room temperature, the tetrahydrofuran is distilled off in vacuo, the residue is taken up in water, and the resulting precipitate is filtered off with suction and dried.