反应详情

A solution of allyl 2-[(3S,4R)-4-[(1R)-4-{(2S)-1-allyloxycarbonylpyrrolidin-2-yl}-4-hydroxy-1-methyl-2-oxobutyl]-3-{(1R)-1-t-butyldimethylsilyloxyethyl}-2-oxoazetidin-1-yl]-2-triphenylphosphoranylideneacetate (2.36 g) in degassed toluene (120 ml) was heated to reflux for 8 hours. After cooling, the toluene was evaporated to give a residue of allyl (4S,5R,6S)-3-[2-{(2S)-1-allyloxycarbonylpyrrolidin-2-yl}-2-hydroxyethyl]-6-[(1R)-1-t-butyldimethylsilyloxyethyl]-4-methyl-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate and the residue was taken up into dichloromethane (90.0 ml). To the mixture were added dropwise triethylamine (1.02 ml) and methane sulfonyl chloride (0.52 ml) at 5° C. with stirring and the stirring was continued for 30 minutes at 5° C. To the resultant mixture was added 1,8-diazabicyclo[5.4.0]-7-undecene (3.36 ml) and the resultant mixture was allowed to warm to around 40° C. After stirring at 40° C. for 2 hours, the mixture was diluted with ethyl acetate and washed in turn with aqueous ammonium chloride, water and brine, and dried over magnesium sulfate. Removal of the solvent gave a residue, which was chromatographed on silica gel (150 ml) eluting with a mixture of n-hexane and ethyl acetate (9:1-4:1 V/V) to give allyl (4S,5R,6S)-3-[(E)-2-{(2S)-1-allyloxycarbonylpyrrolidin-2-yl}ethenyl]-6-[(1R)-1-t-butyldimethylsilyloxyethyl]-4-methyl-7-oxo-1-azabicyclo[3.2.0]-hept-2-ene-2-carboxylate (1.12 g).

1. temperatureto reflux for 8 hours
2. temperatureAfter cooling
3. customthe toluene was evaporated