Reaction Steps
4-[(3-n-Propyl-5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-2-naphthyl)carbonyl]benzoic acid methyl ester (2.7 mmol) in THF (25 mL) was treated with methyltriphenylphosphonium bromide/sodium azide (1.2 g, 3.1 mmol) and the solution was allowed to stir at ambient temperature for 3 h. The reaction was quenched with saturated aqueous NH4Cl and diluted with EtOAc. The organic solution was separated and washed with water and brine, dried (MgSO4), filtered, and concentrated to give a yellow oil. The crude product was crystallized (CH2Cl2/hexanes) to give 4-[(3-n-propyl-5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-2-naphthyl)ethenyl] benzoic acid methyl ester as white crystal (78%): TLC (20% ethyl acetate: 80% hexanes) Rf 0.8; mp 120-121° C.; 1H-NMR (400 MHz, CDCl3) δ7.94 (½ABq, J=8.0 Hz, 2H, ArH), 7.33 (½ABq, J=8.0 Hz, 2H, ArH), 7.09 (s, 1H, ArH), 7.08 (s, 1H, ArH), 5.80 (s, 1H, olefinic), 5.30 (s, 1H, olefinic), 3.90 (s, 3H, OCH3), 2.24 (t, J=8.0 Hz, 2H, CH2), 1.70 (s, 4H, 2CH2), 1.39 (m, 2H, CH2), 1.30 (s, 6H, 2CH3), 1.26 (s, 6H, 2CH3), 0.73 (t, J=7.5 Hz, 3H, CH3), Anal. (C27H34O2) C, H. The ester was hydrolized using the standard conditions of Example 1 to yield 4-[(3-n-propyl-5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthyl)ethyl]benzoic acid (102). Crystallization gave white crystals (83%): TLC (10% MeOH-90% CHCl3) Rf 0.5; mp 263-265° C. 1H-NMR (400 MHz, CDCl3) δ8.00 (½ABq, J=8.0 Hz, 2H, ArH), 7.09 (s, 1H, ArH), 7.08 (s, 1H, ArH), 5.81 (s, 1H, olefinic), 5.31 (s, 1H, olefinic), 2.23 (t, J=8.0 Hz, 2H, CH2), 1.70 (s, 4H, 2CH2), 1.39 (m, 2H, CH2), 1.30 (s, 6H, 2CH3), 1.26 (s, 6H, 2CH3), 0.73 (t, J=7.5 Hz, 3H, CH3), FAB-MS m/z 377 (MH+); Anal. (C26H32O2) C, H.
