Enantioselective γ‐Addition of Pyrazole and Imidazole Heterocycles to Allenoates Catalyzed by Chiral Phosphine.

Chiral phosphines were found to catalyze the enantioselective asymmetric γ‐addition of heteroaromatic compounds to allenoates in good yields with high enantiomeric ratios and regioselectivity in the presence of (S)‐BINOL. Both pyrazole and imidazole could be employed in this process. The synthetic value of these γ‐addition products was demonstrated by the preparation of biologically relevant molecules and structural scaffolds. Remarkably, the synthetic utility of this strategy was demonstrated through a two‐step synthesis of a Janus kinase (JAK) inhibitor. Value added: A highly efficient γ‐addition reaction was developed that gives high yields with excellent enantiomeric ratios by using a phosphine catalyst system. The synthetic utility of this strategy is demonstrated by the preparation of biologically relevant molecules such as a Janus kinase (JAK) inhibitor. [ABSTRACT FROM AUTHOR]