73 アルミナを用いる共役E,Z-ジエン化合物の立体選択的合成

概要

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(2E,4Z)-Dienoic esters are important compounds having utility as aroma agents for food, drinks, and tobacco. Certain insect pheromones such as bombykol (5) and megatomoic acid (7) also have conjugated E,Z-diene systems. We report here an experimentally simple and economically feasible synthesis of (2E,4Z)-dienoic esters 11 and the application of this approach to syntheses of several natural products such as aroma agents of food, insect pheromones, and metabolites of arachidonic acid. The method merely involves the thermal treatment of β-allenic esters 10 with alumina in an aprotic solvent to induce a prototropic rearrangement to give 11 in good yield with 91-100% stereoselectivity. We applied this method for the total syntheses of some natural products such as ethyl (2E,4Z)-decadienoate (1), (2E,4Z)-decadienal (2), (2E,4Z)-heptadienal (3), isochavicine (4), bombykol (5), (7E,9Z)-dodecadien-1-yl acetate (6), megatomoic acid (7), and leukotriene A_4 methyl ester (8). We also report highly stereoselective rearrangements of 11 to 3E,5E-dienoates and of 2E,4E-dienoates to 3E,5Z-dienoates with lithium diisopropylamide (LDA) at low temperature (-80--100℃).
天然有機化合物討論会の論文
1983-09-15