Isobutyl chloroformate → 3-[[5-(Azidomethyl)tetrahydro-3-furanyl]thio]-4-methyl-6-[1-[[(2-methylpropoxy)carbonyl]oxy]ethyl]-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylic acid (4-nitrophenyl)methyl ester

Participants

Reaction Conditions

Reaction Steps

Using anhydrous conditions, 1.25 g of product from Example 45 in 27 ml of anhydrous tetrahydrofuran, is cooled to -78° C. under argon. 0.325 ml of isobutyl chloroformate is added, followed by 2.7 ml of lithium bis(trimethylsilyl)amide. The reaction mixture is stirred at -78° C. for 1 hour, followed by stirring at -55° C. for another hour and then concentrated in vacuo. The residue is purified by chromatography (Silica Gel: 50% ethyl acetate/hexane) to give 1.22 g of the desired product.

Provenance & Evidence