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Silver/ThioClickFerrophos-Catalyzed Enantioselective Conjugate Addition and Cycloaddition of Glycine Imino Ester with Nitroalkenes

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posted on 07.09.2012, 00:00 by Kazumi Imae, Takashi Konno, Kenichi Ogata, Shin-ichi Fukuzawa
We applied the combination of AgOAc with ThioClickFerrophos, the chiral ferrocenyl triazole-based P,S-ligand, to the reaction of glycine imino ester with nitroalkenes. The conjugate addition of the imino methyl ester preferentially produced anti-α-imino-γ-nitrobutyrates in good yields with high enantioselectivities (ee) of up to 99% at −25 °C in THF in the presence of triethylamine. Meanwhile, the pyrrolidine cycloadducts were obtained as major products in good yields with high enantioselectivities (up to 96% ee) using tert-butyl imino ester in the absence of triethylamine at room temperature.