The “pull–push” effect of the Bpin moiety in ArE-Bpin reagents (E=Se, S) is demonstrated by the Lewis acid interaction with the carbonyl group of ynones and the concomitant delivery of ArSe or ArS to the electron-deficient alkyne with impressive stereoselectivity. The two component reactivity is carried out in methanol to generate (Z)-β-(arylseleno)-α,β-unsaturated ketones and (Z)-β-(arylsulfuro)-α,β-unsaturated ketones with a consensus between experimental and theoretical understanding of the mechanism.