Monobenzone → (S)-p-Benzyloxy-(1-methylheptyloxy)benzene

Beteiligte Stoffe

Reaktionsschritte

To an argon-flushed flask containing a solution of 3.01 g (15 mmol) of p-benzyloxy-phenol and 1.25 eq of triphenylphosphine in 220 ml in dry dichloromethane, was added a solution of 4.91 g (15.14 mmol) of (R)-2-octanol in 30 ml of dry dichloromethane via syringe. Then 1.20 eq of diethyl azodicarboxylate dissolved in 60 ml of dry dichloromethane was added dropwise for 30 min. The reaction mixture was stirred at room temperature for 19 h, Then 5 drops of water were added and the mixture was stirred for 1 h. The solvent was then evaporated and the residual crude product was triturated in a mixture of hexanes/ethyl acetate [70/30] for 1 h and filtered through a short silica gel pad. The filtrate was evaporated and the product was purified by flash chromatography on silica gel using dichloromethane/hexanes [10/90] as eluent, affording 3.32 g (71%) of (S)-p-Benzyloxy-(1-methylheptyloxy) benzene (Compound 18, Scheme III, R2 =(S)--OCH(CH3)C6H13) as a colorless liquid: Rf [dichloromethane/hexanes 10/90]: 0.13; 1H NMR (300 MHz, CDCl3): δ 0.87(t, 3 H, J=6.6 Hz), 1.20-1.60(m, 12 H), 1.70(m, 1 H), 4.21(m, 1 H), 5.00(s, 2 H), Distorted AA'BB' System [6.82(d, 2 H) 6.88(d, 2 H)], 7.30-7.46(m, 5 H); 13C NMR (300 MHz, CDCl3): δ 14.02, 19.77, 22.55, 25.52, 29.26, 31.77, 36.51, 70.63, 74.95, 115.77, 117.35, 127.49, 127.87, 128.55, 137.39, 152.53, 153.01; IR (CHCl3): 3010, 2940, 2850, 1600, 1500, 1475, 1450, 1375, 1230, 1200, 1125, 1025, 925, 825 cm-1 ; Mass spectrum, m/z (rel. Intensity): 312(M+ 7), 212(15), 91(100), 71(5), 57(8), 43(10).

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