Abstract
A technically feasible method has been developed for the synthesis of variety of aryl malononitriles in high yields (70-95%) using the palladium-catalyzed coupling reaction of malononitrile with aryl bromides and chlorides, respectively. The influence a several reaction parameters such as base, ligand, solvent or temperature were investigated in some detail.
Key words
arylation - aryl malononitrile - C-C coupling reaction - Pd catalysis - oxopyrazoline herbicide
References and Notes
1a Cederbaum F, Brunner HG, and Boeger M. inventors; WO 9216510 A1.
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1c Muehlebach M, Glock J, Maetzke T, and Stoller A. inventors; WO 9947525 A1.
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1d Muehlebach M, Glock J, Maetzke T, and Stoller A. inventors; WO 2000047585A1.
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1e Maetzke T, Mutti R, and Szczepanski H. inventors; WO 2000078881 A2.
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Standard Experiment.
Malononitrile (181 mg, 2.75 mmol), t-BuONa (720 mg, 7.5 mmol) and xylene (13 mL) were stirred in a Schlenk tube under argon at r.t. for 1 h. Aryl halide (2.5 mmol) and a mixture of PdCl2 (2.5 µmol) and PCy3 (17.5 µmol) in xylene (2 mL) were added and the reaction mixture was stirred at the required temperature. For the experiments described in Table
[2]
, the product was extracted with NaOH solution and after acidification with HCl, was isolated by filtration. The 1H NMR spectra of all products were in agreement with the proposed structures.
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495
