Tetrahydrofuran → 1-(2-Aminopyridin-3-yl)ethanol

Participants

Reaction Steps

To a dry flask (dried with a heat gun under argon purge) was added dry THF (400 mL) and MeLi-LiBr (137 mL of a 1.5 M solution in Et2O, 204.9 mmol) via cannula. This solution was cooled to −78° C. when a solution of 2-aminopyridine-3-carboxaldehyde (10.0 g, 82.0 mmol) in THF (150 mL) was added dropwise via a pressure equalizing addition funnel over ˜45 min with vigorous stirring (exotherm observed, orange color persisted). Upon complete addition, the solution was allowed to stir for 1 hour at −78° C., at which time TLC (KMnO4 stain with heat) indicated that most of the starting material had been converted to product. The reaction was quenched very carefully with water (200 mL; dropwise initially), diluted with EtOAc (200 mL) and allowed to warm to rt. The layers were separated and the aqueous layer was extracted with 3% MeOH in EtOAc. The combined extracts were dried over sodium sulfate, filtered and concentrated under reduced pressure. The residue was purified by silica gel chromatography (Analogix; 0 to 5% MeOH in EtOAc) to give 7.78 g (68%) of the desired racemic product as a yellow oil that solidified under high vac over several days. This material was separated into its respective enantiomers (>98% ee) by SFC with a chiralcel OD-H (20×250 mm) column (10% EtOH/0.1% isopropylamine in heptane/0.1% isopropylamine).

Provenance & Evidence