ChemInform Abstract: Iron‐Catalyst‐Switched Selective Conjugate Addition of Grignard Reagents: α,β,γ,δ‐Unsaturated Amides as Versatile Templates for Asymmetric Three‐Component Coupling Processes.

Abstract

Enantioselective syntheses O 0031Iron-Catalyst-Switched Selective Conjugate Addition of Grignard Reagents: α,β,γ,δ-Unsaturated Amides as Versatile Templates for Asymmetric Three-Component Coupling Processes. -In the absence of FeCl2, the addition of Grignard reagents to amides incorporating a sugar-derived pyrrolidine unit proceeds exclusively with 1,4-regioselectivity. The stereoselectivity of the subsequent alkylation step is controlled by the proximate chiral amide moiety. In contrast, in the presence of catalytic amounts of FeCl 2 , the addition of arylmagnesium bromides to amides bearing the chiral pyrrolidine Dpp group followed by alkyl halogenides gives 1,6-addition products. -(OKADA, S.; ARAYAMA, K.; MURAYAMA, R.; ISHIZUKA, T.; HARA, K.; HIRONE, N.; HATA, T.; URABE*, H.; Angew. Chem., Int. Ed. 47 (2008) 36, 6860-6864; Dep. Biomol. Eng., Tokyo Inst. Technol., Midori, Yokohama 226, Japan; Eng.) -Klein 51-028