Chlorotrimethylsilane → Methyl 4-(thiazol-2-ylmethyl)benzoate

Participants

Reaction Conditions

Reaction Steps

Zinc dust, <10 micron (2.227 g, 34.1 mmol) was suspended in THF (5 ml), and 1,2-dibromoethane (0.090 ml, 1.048 mmol) was added. The mixture was stirred for 10 min at 70° C. It was then cooled to room temperature, and TMS-Cl (0.100 ml, 0.786 mmol) was added. After 30 min at room temperature, the activated zinc was cooled to 0° C., and methyl 4-(bromomethyl)benzoate) (6.00 g, 26.2 mmol) in THF (20 ml) was added drop-wise over 75 min (˜2 mL every ˜5-7 min). After stirring for another 1 h at 0° C., another portion of THF (25 ml) was added to dilute to ˜0.5 M. The gray suspension was allowed to stand so the remaining zinc solid would settle, and the supernatant was used as bromo[4-(methoxycarbonyl)benzyl]zinc (0.5 M in THF). Palladium(II) acetate (103 mg, 0.457 mmol), and 2-dicylochexylphosphino-2′,6′-dimethoxy-1′,1′,biphenyl (375 mg, 0.915 mmol) were combined in a flask, sealed, and flushed with nitrogen (2×). Degassed THF (15 ml), 2-bromothiazole (0.408 ml, 4.57 mmol), and the freshly prepared 0.5 M bromo[4-(methoxycarbonyl)benzyl]zinc in THF (27.4 ml, 13.72 mmol) were added, and the reaction was stirred at room temperature overnight. The reaction was diluted with saturated NH4Cl and water before being extracted with EtOAc (2×). The combined organic layers were washed with brine, dried over MgSO4, filtered and concentrated in vacuo. Flash chromatography (0-50% EtOAc/hexanes) afforded methyl 4-(1,3-thiazol-2-ylmethyl)benzoate (1.06 g, 4.54 mmol, 99%) as a yellow oil that crystallized upon standing. MS ESI: [M+H]+ m/z 234.0.

Provenance & Evidence