Iridium-Catalyzed,\nHighly Selective Allylation of\nPyrazolones for the Convenient Construction of Adjacent Stereocenters

This paper describes an iridium-catalyzed allylation\nof ring-fused\npyrazolones that proceeds with excellent regio-, diastereo- and enantio-selectivities.\nThe approach exploits unactivated, racemic allylic alcohols as a source\nof allyl building blocks. Asymmetric syntheses of a series of biologically\nrelevant, chiral pyrazolones highlight the utility of the methodology.\nThe use of Cu(OTf)<sub>2</sub> as a co-catalyst greatly enhances the\nregioselectivity of the reaction and permits selective syntheses of\nbranched allylation products.