Reaktionsschritte
Formylation. Hexamethylenetetramine (21 g, 0.15 mol) and 1-hydroxy-3,5,5,8,8-pentamethyl-5,6,7,8-tetrahydronaphthalene were added in one portion with stirring to acetic acid (250 mL) and the mixture was heated at 95°-100° C. for 2 h. After cooling to 80°-85° C., water (250 mL) and concentrated hydrochloric acid (60 mL) were added and the mixture was heated at 95°-100° C. for a further 2 h. The reaction product was then cooled to 20° C., diethyl ether (150 mL) was added and the mixture was stirred vigorously. The organic layer was separated, washed with brine (2×50 mL), neutralized with 5% sodium bicarbonate solution (100 mL), and dried (Na2SO4). The solvent was removed by distillation and the residue was distilled to yield 2-formyl-1-hydroxy-3,5,5,8,8-pentamethyl-5,6,7,8-tetrahydronaphthalene (4a) (18 g), mp 91°-92° C., GLC purity 99%+. 1H-NMR (CDCl3) δ12.92 (1H, s), 10.21 (1H, s), 6.73 (1H, s), 1.68 (3H, s), 1.67 (4H, s), 1.48 (6H, s), 1.32 (6H, s). 13C-NMR (CDCl3) δ194.4 (1C, d), 163.5 (1C, s), 156.5 (1C, s), 138.0 (1C, s), 130.8 (1C, s), 120.1 (1C, d), 116.2 (1C, s), 37.7 (1C, t), 35.3 (1C, s), 34.6 (1C, t), 33.9 (1C, s), 31.0 (2C, q), 27.7 (2C, q), 17.8 (1C, q). IR (KBr) 1615, 1628 cm-1, MS (m/e) 246.2 (M+, 23.9) 231.2 (100.0), 189.1 (19.9), 161.2 (19.2).
