Diastereodivergent 1,3-Dipolar Cycloaddition of α-Fluoro-α,β-Unsaturated Arylketones and Azomethine Ylides: Experimental and Theoretical DFT Studies

1,3-Dipolar cycloaddition of alpha-fluoro-alpha,beta-unsaturated arylketones and azomethine ylides has been experimentally and theoretically investigated. The reaction proceeded in a diastereodivergent fashion: in contrast to our previous results where exo-adducts were obtained under Cu(II) catalysis, herein we have achieved the endo-selective 1,3-dipolar cycloaddition using Ag(I) catalyst. Theoretical DFT calculations have been performed to understand the origin of diastereoselectivity switch, possible mechanism, and geometrical features of organometallic intermediates of both catalytic processes. The free-energy profiles suggested that the Michael addition step is the rate determining step, and the coordination between silver atom and carbonyl oxygen atom of enone is the driving force behind endo-selectivity.