Enamine-directed 1,3-dipolar cycloaddition

Finally, a facile and regioselective synthesis of rimonabant was accomplished through an enamine-directed 1,3-dipolar cycloaddition." In the presence of triethylamine, hydrazonoyl iodide was converted into the nitrile imine in situ. The subsequent 1,3-dipolar cycloaddition with the morpholine enamine provided the 1,5-diarylpyrazole, which was transformed into rimonabant. 

Triazolines which are formed as intermediates after the 1,3-dipolar cycloaddition of azides to enamines cannot be isolated but directly undergo elimination to give triazoles. 

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