Iridium-catalyzed asymmetric allylic amination

Subsequently they utilized the cobalt-mediated asymmetric synthesis of [7]helicene-like molecules described above in helicene-based phosphite ligand synthesis. The application of ligand P,S)-2 to rhodium-catalyzed asymmetric hydro-formylation revealed excellent regioselectivity, although the enantioselectivity was low (Scheme 10.14) [15]. For iridium-catalyzed asymmetric allylic amination, the... 

I 9 Iridium-Catalyzed Asymmetric Allylic Substitutions Table 9.2 Ir-catalyzed asymmetric allylic aminations. 

More recently, Hartwig and coworkers reported iridium-catalyzed, asymmetric aminations of allylic alcohols in the presence of Lewis acid activators [103]. The addition of molecular sieves and Nb(OEt)5 or catalytic amounts of BPh3 activated the allylic alcohol sufficiently to allow allylic amination reactions to occur in high yield, branched-to-linear selectivity, and enantioselectivity (Scheme 29). Without the activators, only trace amounts of product were observed. 

A diverse group of secondary and tertiary amines are readily synthesized from the reaction of primary and secondary amines with allylic carbonates in the presence of preformed iridium metalacycles, but the direct synthesis of primary amines via iridium-catalyzed allylic amination requires the use of ammonia as a nucleophile. The asymmetric allylation of ammonia had not been reported until very recently, and it is not a common reagent in other metal-catalyzed reactions. Nonetheless, Hartwig and coworkers developed the reactions of ammonia with allylic carbonates in the presence of la generated in situ [89]. Reactions conducted in the initial work led exclusively to the products from diallylation (Scheme 16). Further advances in... 

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