Hydrochloric Acid → 2-Naphthol

Acrylic acid (1.36 mL, 20.0 mmol) was added to a solution in which 2-naphthol (1.44 g, 10.0 mmol) and AMBERLIST (produced by Aldrich, strong acid, 1.0 g) serving as an ion-exchange resin were dissolved into toluene (30 mL), while the solution was agitated. The resulting mixed solution was refluxed for a day. The resulting suspension was filtrated through celite, and the solvent was removed by distillation in a vacuum. The residue was refined by silica gel flash chromatography (dissolution medium hexane-EtOAc=20:1 (v/v)) to obtain a pyran derivative (1.78 g, 9.0 mmol, yield 90%). A solution in which the resulting pyran derivative (1.78 g, 9.0 mmol) was dissolved into THF (40 mL) was blended with 1-N LiOH (30 mL) and the resulting reaction mixed solution was agitated at room temperature for 6 hours. The resulting reaction mixed solution was poured into 1-N HCl (100 mL), extraction with EtOAc was performed two times, and washing was performed with a saline solution. Organic layers were mixed and dried with anhydrous Na2SO4. The solvent was removed by distillation in a vacuum. The residue was refined by silica gel flash chromatography (dissolution medium hexane-EtOAc=4:1 to 1:1 (v/v)) to obtain 2-Naphthol compound S2, that is, 3-(2-hydroxynaphthalen-1-yl)propanoic acid (4.05 g, 18.7 mmol) at a yield of 62%. The spectrum data thereof are as described below. In this regard, various 2-naphthol compounds used as starting materials in examples described later were synthesized by this method.

1. customthe resulting reaction
2. additionmixed solution
3. customThe resulting reaction
4. additionmixed solution
5. washwashing
6. additionOrganic layers were mixed
7. dry with materialdried with anhydrous Na2SO4
8. customThe solvent was removed by distillation in a vacuum
9. dissolutionThe residue was refined by silica gel flash chromatography (dissolution medium hexane-EtOAc=4:1 to 1:1 (v/v))

ORD record

ord-fb4d8bd53b75487ca22f6a9abf752b77

Source dataset

uspto-grants-2015_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09000216B2