4-Bromotoluene → 2,6-Dicyano-4'-methylbiphenyl

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

4-Bromotoluene (10.44 mL, 84.9 mmol, 1.2 eq.) was converted to the Grignard reagent (Mg: 3.10 g, 127 mmol, 1.9 eq.) in THF (50 mL) and then added to a stirred mixture of freshly fused zinc (II) chloride (9.34 g, 68.5 mmol, 1 eq.) in THF (50 mL) at such a rate as to maintain the temperature at 18° C. In another flash, bis(triphenylphosphine)nickel(II)-chloride (1.10 g, 1.7 mmol, 0.025 eq.) and THF (5 mL) were mixed and cooled to 0° C. Diisobutylaluminum hydride (1M in THF, 3.37 mL, 3.4 mmol, 0.049 eq.) was added to the black mixture of Ni catalyst and THF. After warming to 20° C., 1-bromo-2,6-dicyanobenzene (T. D. Krizan, J. C. Martin J. Org. Chem., (1982) 47, 2681) (0.95 g or 6.7% of the total amount to be coupled, 4.6 mmol, 0.067 eq.) in a minimum of THF was added to the Ni catalyst and stirred for 15 min. The Grignard solution was cooled to 6° C. and then to it the Ni catalyst mixture was transferred via cannula. The remaining 1-bromo-2,6-dicyanobenzene (13.16 g, 63.9 mmol, 0.933 eq.) in a minimum of THF was finally added to the Grignard+Ni catalyst mixture. After stirring overnight at 25° C., the mixture was diluted with ethyl acetate (400 mL) and washed with water (2×200 mL) and brine (1×200 mL). The ethyl acetate layer was dried (MgSO4) and the solvent removed in vacuo to yield a yellow solid. Chromatography in 75:25 hexane/ethyl acetate to 100% ethyl acetate followed by recrystallization from hexane/ethyl acetate yielded 8.46 g of a white solid; m.p. 184.0°-186.0° C. NMR (CDCl3): δ7.98 (d, 2H, J=9 Hz); 7.58 (t, 1H, J=9 Hz); 7.45 (d, 2H, J=9 Hz); 7.37 (d, 2H, J=9 Hz); 2.44 (s, 3H). Anal. calcd. for C15H10N2 : C, 82.55; H, 4.62; N, 12.84. Found: C, 82.34; H, 4.78; N, 12.87.

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