Methanol → (9H-fluoren-9-yl)methyl 4-hydroxy-2-(hydroxymethyl)pyrrolidine-1-carboxylate

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Reaction Steps

To a solution of N-fmoc-trans-4-hydroxy-L-proline (13.4 g, 38.1 mmol) in 250 ml THF was added borane-methyl sulfide (78 mmol, 5.78 g, 7.22 mt) dropwise at room temperature. After the evolution of H2 had ceased, the solution was heated to reflux with mechanical stirring. After 1 hour a white precipitate had formed. Methanol was carefully added, and the resulting solution refluxed for a further 15 minutes. The solution was cooled to room temperature, the solvents evaporated under reduced pressure, and the residual gum coevaporated with 2×100 ml methanol (MeOH). The resulting crystalline product weighed 12.0 g (35.3 mmol, 93%). 1H NMR: (CDCl3, 200 MHz) δ 7.85-7.25 (8H, m, ARH), 4.50-4.10 (5H, m, ArCHCH2, H3, H5), 3.80-3.40 (4H, m, 2 H2, 2 H6), 2.15-1.95 (1H, m, H2a), 1.80-1.60 (1H, m, H2b).

Provenance & Evidence