tert-Butyl acetate → Lithium Hexamethyldisilazide

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

A solution of LiHMDS in toluene was prepared by the addition of n-BuLi (357 mL of a 1.6 M solution in hexanes, 571 mmol) to a cold (−78° C.) solution of HMDS (120.5 mL, 571 mmol) in toluene (700 mL). After 30 min, the reaction mixture was allowed to warm up to 10° C. over 1 h. The solution was then transferred via a cannula to a flame-dried, three-neck flask under N2 containing Pd2dba3 (4.18 g, 4.57 mmol) and (2′-dicyclohexylphosphanylbiphenyl-2-yl)-dimethylamine (3.77 g, 9.59 mmol). The mixture was stirred for 15 min at 15° C., cooled to −10° C. and t-butylacetate (70.5 mL, 525.4 mmol) was added dropwise. After 10 min, 3-chloro-4-iodobenzotrifluoride (70 g, 228.4 mmol) was added and the reaction mixture was warmed up to 28° C. After stirring at this temperature for 1.5 h, the mixture was filtered through silica gel, using toluene as eluent, and the solvent was removed in vacuo. The residue was purified using flash chromatography (silica gel, 98:2 hexanes:EtOAc) to yield (2-chloro-4-trifluoromethylphenyl)-acetic acid tert-butyl ester as a solid.

Herkunft & Nachweise