Diisopropylethylamine → (2S,4R)-tert-butyl 2-(N-(hex-5-enyl)-N-methyl-carbamoyl)-4-hydroxypyrrolidine-1-carboxylate

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Reaction Steps

To a cold solution of cis-N-Boc-4-hydroxy-L-proline (10 g, 1 eq.), 0-(benzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium tetrafluoroborate (TBTU 15.5 g, 1.12 eq.) and N-methylhex-5-en-1-amine tosylate salt 32a (13.6 g, 1.1 eq.), which was prepared according to Scheme 13 as described herein, in DMF (80 mL) containing DIPEA (29.4 mL, 3.9 eq.) was added dropwise under nitrogen at 0° C. The reaction mixture was stirred overnight at room temperature, and then quenched with water and extracted with diethyl ether. The organic layer was washed with brine, dried over magnesium sulfate, and concentrated under reduced pressure. The residue was purified by chromatography on silica gel to yield compound 48 as a rose powder in 95% yield. 1H NMR (DMSO-d6, 400 MHz): δ (ppm) 1.29-1.3 (m, 9H), 1.33-1.55 (m, 4H), 1.70-1.80 (m, 1H), 1.97-2.12 (m, 3H), 2.77-2.97 (m, 3H), 3.15-3.40 (m, 4H), 4.22 (br s, 1H), 4.50-4.62 (m, 1H), 4.90-5.04 (m, 3H), 5.71-5.83 (m, 1H); MS (ESI+): m/z=327 (MH+).

Provenance & Evidence