Dimethyl acetylenedicarboxylate → Dimethyl-2-{[(amino-{(2S)-1-[(benzyloxy)carbonyl]-4,4-difluoropyrrolidin-2-yl}methylidene)amino]oxy}but-2-enedioate

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Reaction Steps

A solution of benzyl-(2S)-2-[amino(hydroxyimino)methyl]-4,4-difluoropyrrolidine-1-carboxylate and dimethylacetylendicarboxylate (1.2 eq.) in chloroform was refluxed for 1 hour under nitrogen and the solution was concentrated. Residue was purified by flash chromatography on silica gel, (eluent: petroleum ether:ethyl acetate=7.5:2.5), to give the desired product as a 3:1 mixture of two isomers by 1H NMR.

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