1-Bromo-4-(methylsulphonyl)benzene → 6-chloro-N-(4-methylsulfonylphenyl)pyrazin-2-amine

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

_1-bromo-4-(methylsulfonyl)benzene (4.70 g, 19.99 mmol)_ _then_ _cesium carbonate (8.47 g, 25.99 mmol)_ _ were successively added to a solution of __6-chloropyrazin-2-amine (2.59 g, 19.99 mmol)_ _ _ _1,4-dioxane (75 ml)_ _into a microwave reactor._ _The mixture was purged by bubbling nitrogen for 5 minutes, then_ ___(9,9-dimethyl-9H-xanthene-4,5-diyl)bis(diphenylphosphine) (0.509 g, 0.88 mmol)_ _and_ _diacetoxypalladium (0.099 g, 0.44 mmol)_ _were added , the mixture was degassed by vacuum/nitrogen three times, then heated to _ _80 °C_ _in an heating block for 2 hours then at __90 °C_ _for 30 min and a further 1 hour heating at __85 °C_ _._ After cooling the mixture was diluted with ethylacetate , filtered , the solid washed with ethyl acetate, the organic solution was washed with water, pre- dried with brine and dried over MgSO4 , filtrated and concentrated in vacuo.The solid was taken up with ethylacetate ( 50 ml) stirred 15 min , and diluted with diethylether until some trouble occured; the solid was filtered and the procedure was repeated twice The solid was dried under vacuum ( 1 mmHg/1 hr /50°C ) to afford 6-chloro-N-(4-(methylsulfonyl)phenyl)pyrazin-2-amine (3. 15g, 55.5% , purity uv 98.6% ). The filtrate was concentrated and purified by flash chromatography on silica gel eluting with 0 to 3% methanol in dichloromethane. The solvent was evaporated to dryness to afford 6-chloro-N-(4-(methylsulfonyl)phenyl)pyrazin-2-amine (1.95 g,34.4% uv purity 94.6%) as a white solid. Nevertheless the 2 batches were combined to afford 6-chloro-N-(4-(methylsulfonyl)phenyl)pyrazin-2-amine (5.10 g, 90 %)

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