Boron trifluoride etherate → HCID 13422895, compound

Participants

Reaction Steps

0.41 ml of boron trifluoride etherate was added to a suspension of 4.70 g (25 mmols) of (1R, 5S)-3-phenyl-4-oxa-2,6-diazabicyclo[3.2.0]hept-2-en-7-one and 14.3 g (125 mmols--5 equivalents) of methyl 4-hydroxy-2-butinoate (R. A. Earl, Organic Synthese 60, 81) in 40 ml of anhydrous methylene chloride at room temperature. The mixture was stirred at room temperature for 1 hour, whereupon a clear solution formed. The solution was then poured into dilute NaHCO3 solution, the mixture was extracted with methylene chloride and the extracts were washed with water and dried over MgSO4. After the solvent had been evaporated off in vacuo and the residue had been filtered on 120 g of silica gel (toluene:ethyl acetate 2:3), 4.74 g (63%) of methyl 4-[3(R)-benzoylamino-2-azetidinon-4(R)-yloxy]-2-butinoate were obtained as colorless crystals, melting point: 142°-143° C, RF : 0.29 (toluene:ethyl acetate 2:3), [α]D20 =18.37° (1.0345 percent in acetone).

Provenance & Evidence