1-Pyrrolidinecarboxylic acid, 2-oxo-, 1,1-dimethylethyl ester → tert-butyl 5-(7-fluoro-2,3-dihydrobenzo[b][1,4]dioxin-5-yl)-2,3-dihydro-1H-pyrrole-1-carboxylate

Participants

Reaction Conditions

Reaction Steps

A solution of isopropyl magnesium chloride in THF (2M, 5.39 mL, 10.78 mmol) was added to a solution of 5-bromo-7-fluoro-2,3-dihydrobenzo[b][1,4]dioxine (Int-53) (1 g, 4.31 mmol) in THF (10 mL) at −45° C. drop-wise and then allowed it to warm up to 5° C. over a period of 1 h. The reaction mixture was cooled again to −45° C. and a solution of tert-butyl 2-oxopyrrolidine-1-carboxylate (1.6 g, 8.62 mmol) in THF (10 mL) was added drop-wise maintaining the temperature at −45° C. The reaction mixture was warmed to 25° C. and stirred for 1 h and then quenched with saturated NH4Cl solution (100 mL). The reaction mixture was extracted with ethyl acetate (3×30 mL) and the organic layer was dried over anhydrous sodium sulphate and concentrated under reduced pressure and purified by column chromatography (using silica gel and 20% ethyl acetate Hexane as eluent) to afford tert-butyl 5-(7-fluoro-2,3-dihydrobenzo[b][1,4]dioxin-5-yl)-2,3-dihydro-1H-pyrrole-1-carboxylate (Int-54). MS (ESI) m/z 340 (M−+1).

Provenance & Evidence