1-O-tert-butyl 4-O-(2,5-dioxopyrrolidin-1-yl) butanedioate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Referring to Scheme 4, to a solution of 1.74 g (10 mmol) of tert-butyl hydrogen succinate (Buchi, G.; Roberts, C. J. Org Chem., 33:460, 1968) and 1.15 g (10 mmol) of N-hydroxy-succinimide in anhydrous tetrahydrofuran (20 ml) was added 2.06 g (10 mmol) of 1,3-dicyclohexylcarbodiimide. After stirring at room temperature overnight, the reaction was filtered to remove the dicyclohexylurea by-product. The filtrate was concentrated in vacuo to give a residue. Chromatography on silica gel using ethyl acetate-hexane (1:1), provided 2.3 g (84% yield) of tert-butyl succinimidyl succinate (4a) as a white solid. TLC: Rf 0.50 (ethyl acetate-hexane 1:1); NMR (d6 -DMSO) a 1.39(s, 9H), 2.56(m, 2H), 2.80(bs, 4H), 2.86 (m, 2H). the reaction was filtered to remove the dicyclohexylurea by-product The filtrate was concentrated in vacuo to give a residue

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Referring to Scheme 4, to a solution of 1.74 g (10 mmol) of tert-butyl hydrogen succinate (Buchi, G.; Roberts, C. J. Org Chem., 33:460, 1968) and 1.15 g (10 mmol) of N-hydroxy-succinimide in anhydrous tetrahydrofuran (20 ml) was added 2.06 g (10 mmol) of 1,3-dicyclohexylcarbodiimide. After stirring at room temperature overnight, the reaction was filtered to remove the dicyclohexylurea by-product. The filtrate was concentrated in vacuo to give a residue. Chromatography on silica gel using ethyl acetate-hexane (1:1), provided 2.3 g (84% yield) of tert-butyl succinimidyl succinate (4a) as a white solid. TLC: Rf 0.50 (ethyl acetate-hexane 1:1); NMR (d6 -DMSO) a 1.39(s, 9H), 2.56(m, 2H), 2.80(bs, 4H), 2.86 (m, 2H). the reaction was filtered to remove the dicyclohexylurea by-product The filtrate was concentrated in vacuo to give a residue

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Referring to Scheme 4, to a solution of 1.74 g (10 mmol) of tert-butyl hydrogen succinate (Buchi, G.; Roberts, C. J. Org Chem., 33:460, 1968) and 1.15 g (10 mmol) of N-hydroxy-succinimide in anhydrous tetrahydrofuran (20 ml) was added 2.06 g (10 mmol) of 1,3-dicyclohexylcarbodiimide. After stirring at room temperature overnight, the reaction was filtered to remove the dicyclohexylurea by-product. The filtrate was concentrated in vacuo to give a residue. Chromatography on silica gel using ethyl acetate-hexane (1:1), provided 2.3 g (84% yield) of tert-butyl succinimidyl succinate (4a) as a white solid. TLC: Rf 0.50 (ethyl acetate-hexane 1:1); NMR(d6 -DMSO) δ 1.39(s,9H), 2.56(m,2H), 2.80(bs,4H), 2.86 (m,2H). the reaction was filtered to remove the dicyclohexylurea by-product The filtrate was concentrated in vacuo to give a residue

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Referring to Scheme 4, to a solution of 1.74 g (10 mmol) of tert-butyl hydrogen succinate (Buchi, G.; Roberts, C. J. Org Chem., 33:460, 1968) and 1.15 g (10 mmol) of N-hydroxy-succinimide in anhydrous tetrahydrofuran (20 ml) was added 2.06 g (10 mmol) of 1,3-dicyclohexylcarbodiimide. After stirring at room temperature overnight, the reaction was filtered to remove the dicyclohexylurea by-product. The filtrate was concentrated in vacuo to give a residue. Chromatography on silica gel using ethyl acetate-hexane (1:1), provided 2.3 g (84% yield) of tert-butyl succinimidyl succinate (4a) as a white solid. TLC: Rf 0.50 (ethyl acetate-hexane 1:1); NMR (d6 -DMSO) a 1.39(s, 9H), 2.56(m, 2H), 2.80(bs, 4H), 2.86 (m, 2H). the reaction was filtered to remove the dicyclohexylurea by-product The filtrate was concentrated in vacuo to give a residue