On the Reactivity of (−)-(R)-Carvone and (−)-4aα,7α,7aβ-Nepetalactone: Synthesis of New Heterocycles

The 1,3‐dipolar cycloaddition of 4‐chlorobenzonitrile oxide to the unsaturated system of (−)‐(R)‐carvone occurred exclusively at C(8) to give a new isoxazoline derivative. This derivative reacts with NH2OH to yield a new heterocycle, observed for the first time. On the other hand, the addition of 4‐chlorobenzonitrile oxide to the unsaturated lactone (−)‐4aα,7α,7aβ‐nepetalactone gave, in a good yield, also a new heterocycle, again obtained for the first time. The terpenoid (−)‐(R)‐carvone and iridoid (−)‐4aα,7α,7aβ‐nepetalactone were isolated from Moroccan species Mentha viridis (L.) and Nepeta tuberosa (L.), respectively. The new heterocycles obtained were identified by combination of chromatographic and spectroscopic methods.