Boron trifluoride etherate → HCID 57213227, compound

Participants

Reaction Steps

A mixture of 4-(2-benzyloxyethyl)-3-ethyl-2-azetidinone (11.65 g), 2-methoxypropene (7.1 ml), borontrifluoride etherate (0.5 ml) in anhydrous toluene (87 ml) is stirred at room temperature for 31/2 hours. Then potassium t-butoxide (3.13 g) is added at room temperature monitoring the epimerization by means of gas-chromatographic assays. After one hour, 40% acetic acid (30 ml) is added and the mixture is heated to 75° C. for two hours and allowed to stand at room temperature overnight. The aqueous acidic phase which separates is extracted with toluene (two 30-ml portions) and the toluene extracts are combined, dried over Na2SO4 and concentrated to dryness under vacuum yielding 10.5 g of crude 4-(2-benzyloxoethyl)-3-ethyl-2-azetidinone which contains 90% of the trans-isomer (estimated by N.M.R.).

Provenance & Evidence