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Updated: Jan 29, 2026

Negative Additive Manufacturing of Complex Shaped Boron Carbides
Published on: September 18, 2018
Catalytic asymmetric aza-Michael addition of fumaric monoacids with multifunctional thiourea/boronic acids
Kenichi Michigami1, Hiroki Murakami, Takeru Nakamura
1Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan. takemoto@pharm.kyoto-u.ac.jp.
Abstract:
The first chemical enantioselective synthesis of N-hydroxyaspartic acid derivatives using chiral multifunctional thiourea/boronic acid organocatalysts was developed. A series of fumaric monoacids underwent an intermolecular asymmetric aza-Michael addition of O-alkyl hydroxylamines in excellent regioselectivity. The addition of another carboxylic acid raised the enantiomeric enrichment up to 97% ee. O-Deprotection of the aza-Michael adduct provided an aspartate-derived hydroxylamine fragment applicable for KAHA (α-keto acid-hydroxylamine) ligation.
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