Synthesis of Δ2-pyrazolines and Δ3-(1,3,4)-oxadiazolines
Written by sctunisie no commentsThe 1,3-dipolar cycloaddition of 2-diazopropane 1 with enones 2 carried out at -60°C has enabled us to observe, for the first time, the formation of an unexpected derivative of the oxadiazoline 6; normally this compound is difficult to prepare. The synthesis of Δ3-(l ,3,4)-oxadiazoline 6 was obtained via the intermediate of Δ1-pyrazoline 3 which is unstable, but in this case it was stabilised by the formation of the oxadiazoline 6 itself. Nevertheless, at 0°C, the intermediate of Δ1-pyrazoline 3 always rearranged by proton migration to give exclusively the more stable Δ2-pyrazoline 4.
R. Gharbi, Z. Mighri, A. Khemiss
Pages 21-30
