Reaction Steps
A solution of ethyl 1-methyl-15-oxocyclopentadeca-3E,11E-dienecarboxylate (0.180 g, 0.59 mmole) and potassium hydroxide (0.15 g, 2.68 mmole) in 50% aqueous ethanol (3 ml) was heated to 65° C. for 5 hours. The solvents were removed by reduced pressure distillation and to the residue was added 5% aqueous hydrochloric acid and methylene chloride. The mixture was shaken, the layers separated, and the organic layer was dried over anhydrous magnesium sulfate, filtered and evaporated to give the crude product. The crude product was purified by flash chromatography to give 2-methylcyclopentadeca-4E,12E-diene-1-one (0.060 g, 44% yield). C16H26O (234 g/mol): 1HNMR (500 MHz, CDCl3): 1.05 (d, 3H), 1.17 (m, 3H), 1.25-1.41 (m, 3H), 1.97 (m, 4H), 2.08 (m, 2H), 2.27 (m, 1H), 2.36 (m, 1H), 2.46 (m, 1H), 2.52 (m, 1H), 2.59 (m, 1H), 5.32 (m, 3H), 5.46 (m, 1H) ppm. 13CNMR (125 MHz, CDCl3): 17.59, 26.07, 26.72, 27.19, 27.65, 28.74, 30.76, 30.98, 36.59, 42.32, 46.34, 127.81, 129.61, 131.06, 132.12, 213.70 ppm. IR (νmax(cm−1)): 3030(w), 2920(s), 2852(s), 1714(s), 1456(m), 1436(m), 970(s). MS (m/z): 234(M), 219, 191, 177, 163, 149, 135, 121, 109, 95, 81, 67, 55, 41.
