Benzene → methyl [(3R,4R)-3-benzyloxycarbonylamino-4-allyl-2-oxoazetidin-1-yl]-3-methylbut-2-enoate

Participants

Reaction Steps

5.05 g (21.2 mmol) of (3R,4R)-3-amino-1-(1-methoxycarbonyl-2-methyl-1-propenyl)-4-(2-propenyl)-2-azetidinone [6] was dissolved in 30 ml of dioxane, and a dioxane solution (60 ml) of 6.4 g (23.3 mmol) of S-4,6-dimethylpyrimidin-2-ylthiocarbonate was added dropwise to the solution at room temperature. The mixture was stirred at room temperature for 16 hours. Benzene (100 ml) was added to the reaction solution, and the insoluble materials were separated by filtration. The filtrate was concentrated, and the resulting syrup was dissolved in a small amount of methylene chloride. The solution was adsorbed on a column of silicas gel (500 g), and the column was eluted stepwise with benzene and benzene/ethyl acetate (10/1, 5/1 and 3/1). Fractions in the eluates which showed a UV absorption at an Rf of 0.20 in TLC developed with benzene/ethyl acetate (4:1) were collected and concentrated under reduced pressure to give 7.66 g (97%) of the captioned compound as a colorless syrup.

Provenance & Evidence