Water → 4-(1,3-Thiazol-2-yl)benzaldehyde

Participants

Reaction Conditions

Reaction Steps

Under argon, 9.2 g (379 mmol) of magnesium are placed in 84 ml of THF and heated to 60° C. A solution of 82.6 g (357 mmol) of 4-bromo-benzaldehyde dimethyl acetal (for preparation see J. Org. Chem. 56, 4280 (1991)) in 677 ml of THF is then added dropwise thereto in the course of 30 min and the mixture is stirred at boiling temperature for a further 40 min. The Grignard solution is cooled, decanted into a dropping funnel and added dropwise in the course of 30 min to a reddish suspension of 31.7 ml (338 mmol) of 2-bromo-thiazole and 5.39 g (9.95 mmol) of 1,3-bis(diphenylphosphino)propane-nickel(II) chloride (Aldrich; Milwaukee/USA) in 1.68 liters of THF. The reaction mixture is stirred at RT for 12 hours; a further 5.39 g of 1,3bis(diphenylphosphino)-propane-nickel(II) chloride are added and stirring is continued for a further 7 hours. 840 ml of water are added, stirring is carried out for 10 min, the THF is evaporated off in a rotary evaporator and the residue is stirred in 1.0 liter of diethyl ether and 340 ml of 2N HCl for 1.5 hours. The aqueous phase is separated off and extracted twice with ethyl acetate. The organic phases are washed twice with 0.5N HCl, water, sat. NaHCO3 solution, water and brine, dried (Na2SO4) and concentrated by evaporation. Chromatography (SiO2; hexane/ethyl acetate=4:1) and digestion in hexane yield 4-(thiazol-2-yl)-benzaldehyde; TLC: Rf=0.21 (hexane/ethyl acetate=3:1); m.p. 91-92° C.

Provenance & Evidence