2,6-Lutidine → p-Nitrobenzyl 2-(4-Acetylthio-2-oxo-1-azetidinyl)-2-triphenylphosphoranylideneacetate

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Reaction Steps

To a solution of crude p-nitrobenzyl 2-(4-acetylthio-2-oxo-1-azetidinyl)-2-chloroacetate (92.9 g., 0.249 mole) in dioxane (1200 ml.) were added in succession 2,6-lutidine (31 ml., 0.274 mole) and triphenylphosphine (71.7 g., 0.274 mole). The resulting mixture was stirred at 45°-47° for 18 hours, cooled to 23° and filtered. The filtrate was concentrated on a rotary evaporator to leave a yellow oil which was purified as follows: absorption on a column of silica gel1 and elution with petroleum ether (4000 ml.), methylene chloride (4000 ml.) and ethyl acetate (4000 ml.). The petroleum-ether fraction was discarded since it contained only impurities. The ethyl acetate fraction was concentrated on a rotary evaporator and the oily residue was triturated with diethyl ether to give the title product as a white solid (74.5 g.), m.p. 162°-165°. The methylene chloride eluate was concentrated to dryness and the oily residue again purified by chromatography as above to give 15.0 g. of title product. The combined solids were dissolved in methylene chloride, treated with activated charcoal, concentrated and recrystallized in diethyl ether to give a total of 87 g. (58%) of title product.

Provenance & Evidence