6-Octenal, 3,7-dimethyl-, (3R)- → Citronellol

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

Powdered LiAlH4 (12.5 g, 329 mmol) was introduced into a 5 L round bottom flask along with 2 L of THF (dried over 3 Å molecular sieve). The slurry was stirred mechanically under N2 and the temperature was lowered to 0° C. (R)-citronellal (5, Takasago, Rockleigh, N.J.) (100 g, 648 mmol) was added neat over about 15 min and the residue was rinsed into the flask with an additional 500 mL of THF. Notwithstanding the fact that TLC indicated complete consumption of citronellal, the mixture was warmed to a gentle reflux and subsequently cooled to 0° C. The reaction was worked up by sequential dropwise addition of the following to the vigorously stirring mixture: 12.5 mL water, 12.5 mL 3 M NaOH, and a solution of 37.5 mL water in 37.5 mL THF. After filtration through celite and thorough washing of the solids with MTBE, the solvent was evaporated to yield 116 g of crude citronellol. This oil was distilled (bulb-to-bulb, 120-140° C., 0.8 mm Hg) to give 6 (93.4 g, 92%) as a clear oil, TLC Rf (10% MTBE/petroleum ether) =0.09. 1H NMR (CDCl3) (δ): 5.10 (m, 1H), 3.66 (m, 2H), 2.1-1.8 (m, 3H), 1.68 (s, 3H), 1.7-1.5 (m, 2H), 1.60 (s, 3H), 1.4-1.3 (m, 2H), 1.17 (m, 1H), 0.90 (d, J=6.66 Hz, 3H); 13C NMR (CDCl3) (δ): u: 131.2, 61.0, 39.8, 37.1, 25.4; d: 124.6, 29.1, 25.6, 19.4, 17.6; IR (cm−1): 3331 (b), 2927, 1454, 1377, 1058; MS (m/z, %): 55 (64), 69 (100), 82 (44), 95 (33), 109 (14), 123 (18), 138 (6), 156 (6); HRMS calcd for C10H20O: 156.1514. Found: 156.1514; [α]D17=+3.74 (c 1.02, EtOH).

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