Synthesis of β-branched Morita–Baylis–Hillman-type adducts from 1,3-diaryl-2-propynyl trimethylsilyl ethers and aldehydes catalyzed by potassium tert-butoxide

1,3-Diaryl-2-propynyl trimethylsilyl ethers were easy to isomerize into the corresponding siloxyallenes using a catalytic amount of potassium tert-butoxide under very mild conditions. The siloxyallenes reacted in situ with various aldehydes to afford Z-selective β-branched Morita–Baylis–Hillman-type adducts in a one-pot reaction after acid treatment.