Hydrochloric Acid → Binol

Participants

Reaction Conditions

Reaction Steps

(S,S)-3-[(1-phenyl ethylamino)-methyl]-hexanoic acid (5.0 g) is dissolved in methanol (20 mL) and (RS)-1,1′-bi-2-naphthol (5.75 g) is added to it at room temperature. The mixture is stirred at 50° C. for 1 hour, during which time solid precipitate comes out from the reaction mixture. Reaction mixture is allowed to cool to room temperature and filtered under reduced pressure to obtain 3.5 g of solid complex. Complex is suspended in the biphasic mixture of ethyl acetate (20 ml) and 1N hydrochloric acid (20 ml) and stirred for 30 to 45 min to decompose the complex. Aqueous phase is washed with 10 mL ethyl acetate. Organic phases are mixed together and washed with brine, followed by drying over sodium sulfate. Solvent is evaporated under vacuum to obtain optically pure (5)-1,1′-bi-2-naphthol (1.5 g) having 99% ee.

Provenance & Evidence