反应详情

The crude carboxylic acid is suspended in anhydrous acetonitrate (150 ml) and treated with p-nitrobenzyl bromide (7.56 g, 35 mμol) and triethylamine (4.9 ml, 35 mμol). The resulting solution is kept at room temperature for 2 days and then in a refrigerator for 3 days. The reddish orange solution is evaporated under vacuum and the residue shaken with ethyl acetate (100 ml, 2×50 ml) and filtered to remove triethylammonium bromide. The ethyl acetate filtrate is washed with water (3×100 ml) and brine, dried with magnesium sulfate, filtered, and evaporated under vacuum to an amber oil (13.62 g). Crystallization from diethyl ether affords N-(t-butyldimethylsilyl)-4-[3-(p-nitrobenzyloxycarbonyl)-2-hydroxypropyl]-azetidin-2-one (6.84 g) as an off-white powder. Chromatography of the mother liquors on a silica gel column using 1:1 toluene-ethyl acetate as eluting solvent affords addition product (3.14 g) as an oil which solidifies.

1. waitin a refrigerator for 3 days
2. customThe reddish orange solution is evaporated under vacuum
3. filtrationfiltered
4. customto remove triethylammonium bromide
5. washThe ethyl acetate filtrate is washed with water (3×100 ml) and brine
6. dry with materialdried with magnesium sulfate
7. filtrationfiltered
8. customevaporated under vacuum to an amber oil (13.62 g)
9. customCrystallization from diethyl ether