Diisobutylaluminumhydride → 2-Ethylidene-6-methyl5-hepten-1-ol

Participants

Reaction Conditions

Reaction Steps

Diisobutyl aluminum hydride (22.4 mL of a 1M methylene chloride solution) was added dropwise over a 0.5h period to a cold (-78° C.) solution of ethyl 2-ethylidene-6-methyl-5-heptenoate (2.00g, 0.0102 mol) in methylene chloride (20 mL). The cooling bath was removed and the mixture was stirred at 25° C. for 4h. The reaction mixture was added to a 2:1 mixture of ice and 6N hydrochloric acid (30 mL). The aqueous layer was extracted with methylene chloride (3×15 mL). The extracts were washed sequentially with 2N hydrochloric acid (20 mL), sodium bicarbonate solution (until neutral), brine and dried (sodium sulfate). Evaporation of solvents provided 1.48g of crude product. Chromatography and kugelrohr distillation (bath temp: 90° C., 0.2 mm) provided 1.25g of 2-ethylidene-6-methyl5-hepten-1-ol (GLC purity: 98.5%; the E and Z isomers were not separated). NMR (250 MHz, CDCl3) δ 1.60 and 1.68 (6H,2s), 1.64 (3H, d, J=7Hz), 2.00 (1H, broad s), 2.10 (4H, broad s), 4.01 and 4.14 (2H, 2s, ratio; 85:15; 4.01 peak assigned to E isomer), 5.14 (1H, m), 5.40 and 5.51 (1H, 2q, J=7Hz); IR (film) vmax 3300, 2930, 1440, 1370 cm-1 ; MS m/e 154, 139, 121, 107, 93, 69, 41.

Provenance & Evidence