Acetaldehyde → (R)-1-pentadecen-4-ol

Participants

Reaction Conditions

Reaction Steps

In a 250-ml round bottom flask equipped with septum inlet, bent tube adapter and magnetic stirring bar is placed (-)-B-chlorodiisopinocampheylborane (99% ee, 9.6 g, 30 mM derived from (+)-α-pinene). The reagent (purchased from Aldrich Chemical Co., 940 West Saint Paul Ave., Milwaukee, Wis. 53233), and 30 ml of anhydrous ether were placed under a nitrogen atmosphere. The mixture was cooled to -40° C. and then treated with allylmagnesium bromide (1.1M 22.7 ml, 25 mM). The reaction mixture was then allowed to warm to room temperature. Meanwhile, dodecanal (redistilled, 4.41 ml, 20 mM) was dissolved in 10 ml of anhydrous ethyl ether and cooled to ice-bath temperature (5° C.). The resulting allyldiisopinocampheylborane was cooled to -78° C. after stirring at room temperature for 30 minutes; dodecanal was then slowly added keeping the mixture at -78° C. The mixture was then allowed to warm to room temperature in the same bath overnight. The resulting mixture was cooled to 5° C. and then acetaldehyde (10 ml, 180 mM) was slowly added, with stirring. The mixture was further stirred at room temperature for 18 hours. The resulting organoborane was then oxidized at 5° C. with sodium acetate (20 ml, 60 mM), and hydrogen peroxide (30%, 10 ml). The addition of H2O2 generates an exothermic reaction. The mixture was extracted with diethylether (Et2O) (3×20 ml), and the combined ether extracts were washed with water and a saturated solution of sodium chloride. The extract was dried over anhydrous magnesium sulfate, filtered and the solvent removed. The residue was chromatographed on silical gel (1:15 ethyl acetate/hexane). The pure fractions, as determined by thin layer chromatography (TLC) were pooled, made free of solvents and distilled to provide (R)-1-pentadecen-4-ol (3), a colorless oil with a bp 96° C., 0.5 mm of Hg, 3.39 g, 75% yield. Analysis of the prepared (R)-1-pentadecen-4-ol (3): IR(neat) 3350, 2900, 2860, 1640, 910 cm-1. 1H NMR (CDCl3) δ 0.89 (t, 3H, J=6.4 Hz), 1.28 (bs, 16H), 1.47 (bs, 2H), 2.15 (m, 1H), 2.3 (bm, 1H), 3.65 (bq, 1H), 5.11 (s, 1H), 5.16 (d, 1H), 5.84 (m, 1H).

Provenance & Evidence