Enol ethers Triisobutylaluminum

Chiral ketals of 4-alkylcyclohexanones and of m-3,5-dimethylcyclohexanone with (/ ,/ )-2,4-pentanediol are converted, on treatment with triisobutylaluminum in dichloromethane at 0°C and subsequent acetylation of the first formed alcohol with acetic anhydride, to chiral enol ethers with high yield and good diastereoselectivity82. 

Elimination of Acetals. Treatment of 2,4-pentanediol acetals of meso ketones with Triisobutylaluminum gives enol ethers with high diastereoselectivities (eq 3). ... 

The enantioselective total synthesis of the cyclooctanoid natural product (+)-epoxydictymene was accomplished in the laboratory of L.A. Paquette. The entire tricyclic framework was constructed by the application of a Claisen rerrangement via a chairlike transition state. The precursor for this / 3,37-sigmatropic rearrangement was obtained by treating a lactone precursor with the solution of the Tebbe reagent in the presence of pyridine. The corresponding enol ether was formed in almost quantitative yield, and immediately after isolation it was treated with triisobutylaluminum to effect the Claisen rearrangement. 

Treatment with triisobutylaluminum converts the saturated acetal 6 into the optically active enol ether 770. Cyclopropanation of 7 with the Simmons-Smith reagent then provides the cyclopropanol derivative 8 with a d.r. of 95 5. Even better side discrimination is observed when the more active diiodomethane/diethylzinc system is applied under optimized conditions70 the cyclopropanol derivative is obtained diastereomerically almost pure. 

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