10.1021/acs.orglett.7b03811.s001 Zhiyong Wang Zhiyong Wang Yanzhou Yang Yanzhou Yang Fang Gao Fang Gao Qian Luo Qian Luo Ling Fang Ling Fang Synthesis of 5‑(Trifluoromethyl)pyrazolines by Formal [4 + 1]-Annulation of Fluorinated Sulfur Ylides and Azoalkenes American Chemical Society 2018 Annulation synthesis annulation Trifluoromethyl method Synthesi Fluorinated Sulfur Ylides Azoalkene trifluoromethyl yield diaza Formal sulfur ylides 2018-02-02 04:36:10 Journal contribution https://acs.figshare.com/articles/journal_contribution/Synthesis_of_5_Trifluoromethyl_pyrazolines_by_Formal_4_1_-Annulation_of_Fluorinated_Sulfur_Ylides_and_Azoalkenes/5848566 In situ formed 1,2-diaza-1,3-dienes were used in formal [4 + 1]-annulation reactions with fluorinated sulfur ylides. This protocol provides a novel and efficient method for the synthesis of 5-(trifluoromethyl)­pyrazolines in moderate to excellent yields.