Imidazole → Cis-3-[(R)-1-(tert-butyldimethylsilyloxy)ethyl]-4-trimethylsilylethynyl-2-azetidinone

Participants

Reaction Conditions

Reaction Steps

A cis/trans mixture (1.44 g) of 3-(1-hydroxyethyl)-4-trimethylsilylethynyl)-2-azetidinone is dissolved in N,N-dimethylformamide (15 ml), and imidazole (1.4 g) and tert-butyldimethylsilyl chloride (3.0 g) are added. The mixture is stirred at 60° C. for 2 hours and then poured into a mixture of ethyl acetate (100 ml) and water (50 ml). The organic layer is separated, serially washed with water and aqueous sodium chloride, dried over magnesium sulfate and concentrated under reduced pressure. The residue is subjected to silica gel column chromatography to give 0.62 g of cis-3-[(R)-1-(tert-butyldimethylsilyloxy)ethyl]-4-trimethylsilylethynyl-2-azetidinone, 0.97 g of trans-3-[1-(tert-butyldimethylsilyloxy)ethyl]-4-trimethylsilylethynyl-2-azetidinone and 0.36 g of a cis/trans mixture. The physical characteristics of the cis form are identical with those of the compound obtained in Example 4. Physical characteristics of the trans compound

Provenance & Evidence