Dimethyl Sulfate → 5-Methoxy-1,1,4,4,7-pentamethyl-1,2,3,4-tetrahydronaphthalene

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Methylation. A solution of sodium hydroxide (38 g, 0.95 mol) in water (1 L) was added to a mixture of 1-hydroxy-3,5,5,8,8-pentamethyl-5,6,7,8-tetrahydronaphthalene (109 g, 0.5 mol), dimethyl sulfate (126 g, 1 mol) and Adogen 464* (21.6 g) in methylene dichloride (2 L). The reaction mixture was stirred vigorously at 25°-28° C. for 1 h, after which the organic layer was separated, combined with ammonium hydroxide solution (500 mL, 10%), and stirred vigorously at 20°-25° C. for 0.5 h. The organic layer was then separated and the washing procedure repeated, after which the organic layer was separated, washed with water (2×100 mL), then with brine (50 mL), and dried (Na2SO4). The solvent was removed by distillation and the residue was crystallized from hexane yielding 1-methoxy-3,5,5,8,8-pentamethyl-5,6,7,8-tetrahydronaphthalene (95 g), mp 49°-50° C., GLC purity 99 %+. 1H-NMR (CDCl3) δ6.89 (1H, d, J=1.4 Hz), 6.63 (1H, d, J=1.4 Hz), 3.89 (3H, s), 2.41 (3H, s), 1.74 (4H, m), 1.48 (6H, s), 1.38 (6H, s). IR (KBr) 1273, 1257 cm-1, MS (m/e) 232 (M+, 16.9), 217 (100.0), 175.3 (19.6), 218.6 (16.0).

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