Iridium-Catalyzed, Highly Selective Allylation of Pyrazolones for the Convenient Construction of Adjacent
Shixiang Sun1, Yuqi Zhang1, Martin G Banwell1
1Institute for Advanced and Applied Chemical Synthesis, College of Pharmacy, Jinan University, Guangzhou 510632, Guangdong, China.
Abstract:
This paper describes an iridium-catalyzed allylation of ring-fused pyrazolones that proceeds with excellent regio-, diastereo- and enantio-selectivities. The approach exploits unactivated, racemic allylic alcohols as a source of allyl building blocks. Asymmetric syntheses of a series of biologically relevant, chiral pyrazolones highlight the utility of the methodology. The use of Cu(OTf)2 as a co-catalyst greatly enhances the regioselectivity of the reaction and permits selective syntheses of branched allylation products.
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