Computational studies on the reaction pathways of trifluoromethyloxazolones with both α,β and α,β,γ,δ-unsaturated Fischer carbenes

•The reaction between trifluorometiloxazolones and both α,β-unsaturated and α,β,γ,δ-unsaturated Fischer carbene occurs by steps through the oxazolone ionic form.•Chemoselectivity depends on the used unsaturated system.•QTAIM and DFT chemical descriptors evinces relevant resonant species and preferable reactive sites along the reaction.