Phospholane‐Catalyzed Wittig Reaction

Abstract

Abstract We identified 2‐phenylisophosphindoline 2‐oxide as a suitable and potentially tunable catalyst for the catalytic Wittig reaction of aldehydes with activated organohalides. This catalyst was obtained by a straightforward two‐step synthesis. Trimethoxysilane proved to be an efficient reducing agent for the in situ generation and regeneration of the catalyst from the corresponding phosphane oxide. Sodium carbonate was identified as a suitable base for the transformation. It is noteworthy that the particle size of the sodium carbonate had a tremendous effect on the outcome of the reaction. Under the optimized reaction conditions, 23 aldehydes were converted into the corresponding alkenes in high isolated yields of up to 88 %. Moreover, an asymmetric catalytic Wittig reaction was performed for the desymmetrization of a prochiral diketone.