Acetate → 3-Dipropylamino-8-fluoro-5-methoxychroman

Participants

Reaction Steps

In a round-bottom flask equipped with a magnetic stirrer were placed the crude acetate of 3-amino-8-fluoro-5-methoxychroman (1.18 g; approx. 3.9 mmol) from above, dry methanol (10 mL), propanal (2.8 mL; 39 mmol), glacial acid (pH 3-4) and sodium boronhydride (0.25 g; 3.9 mmol) but with no molecular sieves. The reaction mixture was stirred under nitrogen at room temperature for 1 h. The solution was filtered through Celite and the solvent was evaporated to leave a liquid residue which was diluted with water (25 mL) and extracted with ether (2×100 mL) after adjusting pH to 10-11 with 5M sodium hydroxide. The collected ether phases were dried (K2CO3), filtered and concentrated in vacuo.

Provenance & Evidence