Reaction Steps
Formylation. 1-Methoxy-3,5,5,8,8-pentamethyl-5,6,7,8-tetrahydronaphthalene (50 g, 0.2155 mol) was added to a stirred mixture of hexamethylenetetramine (31.4 g, 0.224 mol) and trifluoroacetic acid (250 mL) at 35°-40° C., under a nitrogen atmosphere. The stirred reaction mixture was heated to 85°-90° C. and maintained at this temperature for 1.5 h. Trifluoroacetic acid was removed by distillation and the residue was poured onto an ice-water mixture (800 mL). The mixture was then stirred for 0.5 h, neutralized with a 10% sodium carbonate solution, and the product extracted with benzene (2×150 mL). The combined extracts were washed with brine (50 mL) and dried (Na2SO4). The solvent was then removed by distillation and the residue crystallized from hexane to provide 2-formyl-1-methoxy-3,5,5,8,8-pentamethyl-5,6,7,8-tetrahydronaphthalene (14 g), mp 78° C. GLC purity 100%. 1H-NMR (CDCl3) δ10.39 (1H, s), 6.93 (1H, s), 3.86 (3H, s), 2.49 (3H, s), 1.63 (4H, s), 1.39 (6H, s), 1.37 (6H, s), 13C-NMR (CDCl3) δ192.1 (1C, d), 165.4 (1C, s), 153.5 (1C, s), 138.3 (1C, s), 135.8 (1C, s), 125.8 (2C, s, d), 66.1 (1C, q) 38.1 (1C, t), 35.3 (1C, s), 34.8 (1C, t), 34.3 (1C, s), 31.7 (2C, q), 29.8 (2C, q), 20.8 (1C, q). IR (melt) 1245, 1682 cm-1, MS (m/e) 260 (M+, 20.8), 246 (18.7), 245 (100.0), 141 (12.3), 128 (13.2), 115 (13.0).
