Hexamethylphosphoramide → HCID 68579426, compound

Participants

Reaction Steps

Lithium diisopropylamide (1.5 M in cyclohexane, 9.22 mL, 13.83 mmol) was added to a solution of 4-(tert-butyldimethylsilanyloxymethyl)-1-(2,4-dimethoxybenzyl)-pyrrolidin-2-one (2.63 g, 6.93 mmol) in THF (41 mL) at −78° C. under nitrogen. After 30 min at −78° C., hexamethylphosphoramide (3.61 mL, 20.7 mmol) was added dropwise. After 30 min at −78° C., methyl 7-iodohept-5-ynoate (5.52 g, 20.7 mmol) in THF (20 mL +3 mL) was added. The reaction mixture was allowed to warm to room temperature. After 18 h at room temperature, the reaction was quenched with saturated aqueous NH4Cl and extracted with EtOAc (3×50 mL). Combined extracts were dried (Na2SO4), filtered and concentrated in vacuo. The crude residue was purified by flash column chromatography on silica gel (40% EtOAc/hexane) to afford 579 mg (16%) of 7-[(3R*,4R*)-4-(tert-butyldimethylsilanyloxymethyl)-1-(2,4-dimethoxybenzyl)-2-oxo-pyrrolidin-3-yl]-hept-5-ynoic acid methyl ester.

Provenance & Evidence