Allyl Alcohol → 3-Allyl 1-tert-butyl 4-oxopyrrolidine-1,3-dicarboxylate

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Reaction Steps

A solution of 1-tert-butyl 3-methyl 4-oxopyrrolidine-1,3-dicarboxylate (48.65 g, 0.20 mol), allyl alcohol (300 mL), and dibutyltin oxide (5.0 g, 20 mmol) in anhydrous toluene (800 mL) was refluxed for 20 h under a Dean-Stark trap with portionwise removal of solvent (total of 200 mL) over the first 6 hours, followed by addition of more allyl alcohol (75 mL) at the end of the first 6 hours. The reaction mixture was concentrated, dissolved in minimal methylene chloride, and loaded onto a silica gel column (700 mL volume) and eluted with methylene chloride, 10%, then 15%, then 20% ethyl acetate/methylene chloride to afford 3-allyl 1-tert-butyl 4-oxopyrrolidine-1,3-dicarboxylate (48.6 g, 90%) as a pale pink oil (NMR and MS as above). This compound (48.47 g, 0.18 mol) was dissolved in anhydrous tetrahydrofuran (200 mL) and added to a stirred solution of Pd(PPh3)4 (4.16 g, 3.6 mmol) in anhydrous tetrahydrofuran (400 mL) under nitrogen, stirred for 4 h, and concentrated. The residue was dissolved in heptane and loaded onto a silica gel column (1000 mL volume) and eluted with 60:35:5 heptane/methylene chloride/ethyl acetate to afford tert-butyl 3-allyl-4-oxopyrrolidine-1-carboxylate (27.93, 69%) as a pale yellow oil (NMR and MS as above).

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