Copper(II)‐Catalyzed Silylation of Activated Alkynes in Water: Diastereodivergent Access to E‐ or Z‐β‐Silyl‐α,β‐Unsaturated Carbonyl and Carboxyl Compounds

Copper(II)‐catalyzed silylation of substituted alkynylcarbonyl compounds was investigated. Through the activation of Me₂PhSiBpin in water at room temperature and open atmosphere, vinylsilanes conjugated to carbonyl groups are synthesized in high yield. A surprising diastereodivergent access to olefin geometry was discovered using a silyl conjugate addition strategy: aldehydes and ketones were Z selective while esters and amides were exclusively transformed into the E products.