Acetic Acid → 5-Hydroxy-7-methyl-6-phenyl-2-naphthalenyl 4-methylbenzenesulfonate

Participants

Reaction Steps

A round-bottomed flask was charged with 3-methyl-6-(methyloxy)-2-phenyl-1-naphthalenyl acetate (6) (5.00 g, 16.34 mmol), acetic acid (100 mL) and 48% aqueous HBr (50 mL). The resultant mixture was stirred between 90° C. and 100° C. for 4 h. The reaction mixture was concentrated under reduced pressure and the residue was neutralized with sat. NaHCO3 (100 mL). The aqueous reaction mixture was extracted with CH2Cl2 (4×150 mL). The combined organic layer was dried (Na2SO4) and concentrated under reduced pressure to afford ˜4.10 g (86%) the crude title product. To a solution of the above obtained crude product (˜1.00 g) in CHCl3 (50 mL) were added pyridine (1 mL), p-toluene sulfonic acid (2 equiv). The resultant mixture was stirred at RT for 36 h. Reaction mixture was diluted with CH2Cl2 (250 mL), washed with 10% aqueous HCl, brine (1×50 mL), and dried (Na2SO4). The organic layer was concentrated under reduced pressure to afford the crude product. The product was purified by SiO2 column chromatography to afford 850 mg (89%) of the title compound (239). 1H NMR (400 MHz, CDCl3): δ 8.08 (d, J=9.2 Hz, 1H), 7.73 (d, J=8.4 Hz, 2H), 7.54 (dd, J1=7.6 Hz, 2H), 7.47 (d, J=7.2 Hz, 1H), 7.39 (d, J=2.0 Hz, 1H), 7.30 (dd, J1=6.4 Hz, J2=6.4 Hz, 4H), 7.22 (br s, 1H), 6.98 and 6.96 (dd, J1=9.2 Hz, J2=2.0 Hz, 1H), 5.25 (s, 1H), 2.44 (s, 3H), 2.16 (s, 3H). LCMS (ESI) m/z 405.22 (M+H)+.

Provenance & Evidence