Diisopropylamine → 3-(2,4-Bis{[2-(trimethylsilyl)ethoxy]methoxy}phenyl)-4-(bromomethyl)-7-{[2-(trimethylsilyl)ethoxy]methoxy}-2H-1-benzopyran-2-one

Participants

Reaction Conditions

Reaction Steps

A 250 mL 3-neck round bottom flask was equipped with a magnetic stirrer, a rubber stopper and an argon inlet/outlet adapter. This vessel was charged with THF (20 mL) via syringe, iPr2NH (1.8 mL, 14.0 mmol) via syringe and cooled to −10° C. in an ice/methanol bath. n-Butyl lithium (1.85 M (titrated) via syringe, 6.3 mL, 11.7 mmol) in hexane was added dropwise via syringe at −10° C., stirred for 15 min at −10° C. To the solution was added 3-[2,4-bis-(2-trimethylsilanyl-ethoxymethoxy)-phenyl]-4-methyl-7-(2-trimethylsilanyl-ethoxymethoxy)-chromen-2-one (5.1 g, 7.8 mol) in THF (20 mL) drop-wise via syringe. The mixture was stirred at −10° C. for 2.5 h. This mixture was added dropwise via syringe to a solution of Br2(0.76 mL, 2 eq) in −78° C. THF (100 mL) via syringe that was contained in a 1-L 3-neck round bottom flask equipped with mechanical stirrer and septum under N2. After the addition was complete, the mixture was stirred for 5 min at −78° C. and then diluted with EtOAc (0.5 L) via syringe, saturated NaHCO3 (50 mL) via syringe and saturated Na2SO3 (100 mL) via syringe. The dry ice/acetone bath was removed and the mixture was allowed to warm to room temperature while stirring. The organic phase was separated and the aqueous phase was back-extracted with EtOAc (2×0.2 L). The combined organic phase was washed with brine (2×0.5 L) and concentrated in vacuo to yield the title compound as a crude semi-solid.

Provenance & Evidence