Tetrahydrofuran → (3R,4R)-1-Benzyl-4-fluoropyrrolidin-3-amine bis(4-methylbenzenesulfonate)

Participants

Reaction Conditions

Reaction Steps

A solution of 1M tetrabutylammonium fluoride in THF (1.27 L, 1.27 mol, 2.5 eq) and (3aR,6aS)-5-benzyl-2,2-dioxo-tetrahydro-1-oxa-2λ6-thia-3-5-diaza-pentalene-3-carboxylic acid t-butyl ester (180 g, 0.508 mol, 1.0 eq) were heated at 60° C. (jacket temperature) for 2 hr. Upon reaction completion, the mixture was partially distilled under vacuum to remove the THF. After concentration to a low stir volume, THF was displaced with EtOAc (2×500 mL). After again reducing to a low stir volume, EtOAc (3.6 L) and p-toluenesulfonic acid monohydrate (396 g, 2.10 mol, 4.1 eq) were charged and heated at 80° C. for 2 hr. The mixture was cooled to 10° C. over 1.5 hr and then granulated at 10° C. for 2 hr. The solid product was filtered and washed with EtOAc (2×900 mL) and dried at 50° C. in a vacuum oven for 12 hr. The title compound was isolated as an air stable crystalline solid in 83% yield (231 g, 419 mmol). 1H NMR (400 MHz, D2O) δ ppm 7.69-7.61 (m, 4 H) 7.56-7.42 (m, 5 H) 7.36-7.29 (m, 4 H) 5.65-5.49 (m, 1 H) 4.47 (br. s., 2H) 4.37-4.23 (m, H) 4.15 (ddd, J=12.8, 8.2, 1.4 Hz, 1 H) 3.88 (dd, J=19.1, 1.2 Hz, 1 H), 3.74 (ddd, J=33.2, 14.0, 5.5 Hz, 1 H) 3.44 (dd, J=12.8, 8.2 Hz, 1 H) 2.34 (s, 6 H). m/z (EI+) for C11H15FN2 194.8 (M+H)+.

Provenance & Evidence