Acetate → 1-Benzyl-3,4 dihydroxy pyrroldine benzene sulfonic acid salt

Participants

Reaction Conditions

Reaction Steps

In a 3N 5 L RBF with overhead stirrer and reflux condenser, the DL-1,4-dibromo butane diol (100 g, 403 mmol), benzyl amine (39.7 ml, 363 mmol), potassium iodide (3.35 g, 20.17 mmol) and diisopropylethylamine (DIPEA, 70.3 ml, 403 mmol) were suspended in 500 mL dioxane and heated to 110° C. overnight. After 17 h cooled at 80° C., added 750 mL 1M aqueous K2CO3 and 750 mL ethtyl acetate (EtOAc). Allowed to cool to 23° C. and separated layers. Extracted with 500 mL EtOAc and then dried combined organics over Na2SO4. Filtered and concentrated to 400 mL solution. Added benzene sulfonic acid (38.3 g, 242 mmol) in 200 mL EtOAc slowly over 1 h. After 16 h at 23° C., cooled to 0° C. and filtered. Washed cake with 200 mL methyl tert-butyl ether (MTBE) and then dried under vacuum at 40° C. for 6 h to give 73.8 g of 1 as an off-white solid (52% yield). 1H NMR (400 MHz, CD3OD) δ 7.85 (m, 2H), 7.65-7.41 (m, 8H), 4.42 (m, 2H), 4.28 (m, 2H), 3.79 (dd, J=12.7, 4.2 Hz, 1H), 3.51 (dd, J=12.2, 3.4 Hz, 1H), 3.38 (d, J=12.2 Hz, 1H), 3.25 (d, J=12.7 Hz, 1H).

Provenance & Evidence