3-(Trifluoromethyl)-substituted (F) 2-vinyl-2-diazocarbonyl compounds, having cis- relationship of functional groups (AlkO2C, CN2), do not undergo 1, 5-electrocyclization, but readily take part in the tandem Staudinger–diaza-Wittig reactions to produce trifluoromethyl- substituted pyridazines, whereas their non-fluorinated analogs (H), with trans-configuration, easily cyclize to pyrazoles, but remain intact under Staudinger–diaza-Wittig reaction ...