Reactions
- Ligand used to prepare a chiral zirconium catalyst useful in asymmetric Strecker reactions.
- Ligand used in the zinc-catalyzed enantioselective Hetero Diels-Alder reaction.
- Ligand used in asymmetric Friedel-Crafts reactions of pyrroles with glyoxylates.
Chemical Properties
white to light yellow crystal powde
Uses
(
S)-(+)-6,6′-Dibromo-1,1′-bi-2-naphthol may be used in the synthesis of (2
R,3
S)-3-phenylisoserine hydrochloride. It may also be used in the synthesis of BINOL-derived chiral ligands with aryl substituents in the 6,6-positions. [BINOL=1,1′-bi-2-naphthol]
General Description
(
S)-(+)-6,6′-Dibromo-1,1′-bi-2-naphthol is an aromatic chiral Bronsted acid.
Synthesis
General procedure for the synthesis of (S)-6,6'-dibromo-1,1'-bi-2-naphthol from (S)-1,1'-bi-2-naphthol: (S)-BINOL (7.20 g, 25.0 mmol, 1.0 eq.) was suspended in dichloromethane (250 mL) at -78 °C. A solution of bromine (3.9 mL, 34.0 mmol, 1.4 eq.) in dichloromethane (40 mL) was added slowly dropwise to the reaction mixture (dropwise time 20-30 min) and stirring was continued at -78 °C for 15 min. The reaction mixture was allowed to warm up slowly to room temperature and the progress of the reaction was monitored by thin layer chromatography (TLC) (about 3 hours) until the reaction was complete. The reaction was quenched by the addition of saturated aqueous sodium thiosulfate (50 mL) and the aqueous layer was extracted with ethyl acetate (3 x 50 mL). The organic layers were combined, dried with anhydrous magnesium sulfate, filtered and concentrated under reduced pressure to remove the solvent. The product was recrystallized by dichloromethane/pentane to afford (S)-6,6'-dibromo-1,1'-bian-2-naphthol as a white solid (10.34 g, 23.3 mmol, 93% yield).1H NMR (300 MHz, CDCl3) δ: 8.03 (d, J = 1.9 Hz, 2H), 7.87 (d, J = 9.0 Hz, 2H), 7.45-7.35 (m, 4H), 6.94 (d, J = 9.0 Hz, 2H), 5.00 (bs, 2H). 13C NMR (75 MHz, CDCl3) δ: 153.0, 131.9, 130.8, 130.7, 130.6, 130.4, 125.9, 119.0, 118.0, 110.7. The analytical data are in agreement with the literature.
References
[1] Journal of the American Chemical Society,
[2] Journal of the American Chemical Society, 2009, vol. 131, p. 3621 - 3630
[3] Angewandte Chemie - International Edition, 2002, vol. 41, # 7, p. 1159 - 1162
[4] Chemical Communications, 2010, vol. 46, # 27, p. 4911 - 4913
[5] Chemical Communications, 2012, vol. 48, # 54, p. 6851 - 6853
