Synthesis of (±)-trixagol by an electrophilic cyclization of an allylsilane

1,5-Dienes containing an allylsilane are cyclized by Lewis acids to methylenecyclohexanes. The trimethylsilyl group exerts a strong activating and directing influence on the regioselectivity of this cyclization. The monocyclic compound 10 was converted into the diterpene, (±)-trixagol (3).[Formula: see text]