A novel competition between C–Se and C–Si cleavages in cyclization of β-seleno-β-silyl-substituted divinyl ketones

Abstract

Reactions of β-seleno-β-silyl-substituted divinyl ketones 2–4 with Lewis acids at room temp. gave phenylseleno and/or trimethylsilyl functionalized cyclopentenones. The use of TiCl₄ or SnCl₄ results in C–Se cleavage leading to 5-(phenylseleno)-3-(trimethylsilyl)cyclopent-2-enones 9–11 as major products. In contrast, using AgBF₄–TMSCI (trimethylsilyl chloride) results in C–Si cleavage to give 3-(phenylseleno)cyclopenten-2-ones 12–14. Lewis acid-dependent competitive cleavage between C–Se and C–Si bonds has been demonstrated.