N-Hydroxyphthalimide → di-tert-butyl 4-[(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)oxy]pyrazolidine-1,2-dicarboxylate

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Reaction Steps

To a mixture of 2-hydroxy-1H-isoindole-1,3(2H)-dione (1.72 g, 10.541 mmol), di-tert-butyl 4-hydroxypyrazolidine-1,2-dicarboxylate 141 (Journal of Antibiotics, 1993, Vol 46, (12), 1866-1882, 1.52 g, 5.27 mmol) and triphenylphosphine (2.76 g, 10.54 mmol) in THF (50 mL) was added DIAD (2.24 mL, 11.59 mmol) slowly at room temperature. The resulting mixture was stirred at room temperature overnight and concentrated to provide a residue, which was subjected to chromatography to give 142 (1.8 g, 79%) as a white foam.

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