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The title catalyst is applied to the asymmetric Michael addition of nitromethane to α,β-unsaturated ketones.

(Z)-3-(2, 4, 5-Trimethoxy-3-methylbenzylidene)-1, 6-dimethylpiperazine-2, 5-dione (7a) was prepared by a simple regioselective C-monomethylation of (Z)-4-(4-methoxybenzyl)-3-(2, 4, 5-trimethoxy-3-methylbenzylidene)-1-methyl-piperazine-2, 5-dione (3) followed by deprotection. Compound 7a was also prepared from (S)-1, 4-diacetyl-3-methylpiperazine-2, 5-dione (8) and the benzaldehyde derivative (9) in five steps as an optically active form. It was shown to be a useful intermediate for the preparation of novel octahydro-1, 5-imino-3-benzazocin-4, 7, 10-trione derivatives having a methyl group at the C-2 position, as ABC ring models of saframycins.

(2R,3S)-3-Vinylmalic acid (VM) was designed as a mechanism-based inhibitor of threo-3-isopropylmalate dehydrogenase (IPMDH), the rate-determining enzyme responsible for the penultimate step in the biosynthetic pathway of the essential amino acid l-leucine. The synthesis of VM was achieved in six steps from diethyl (R)-malate. Besides its weak activity as a substrate, VM was shown to be a mechanism-based inhibitor (KI = 1.20 mM) for IPMDH as deduced from the time-dependent and kinetic analyses. 2-Oxo-3-pentenoate was identified as the enzyme reaction product of VM by GC−MS analysis and 1H NMR spectroscopy, but the supplemented 2-oxo-3-pentenoate was not, in contrast, inhibitive to the enzyme reaction. It seems likely from these results that an activated or nucleophilic amino acid of IPMDH by deprotonation during the ordinary enzyme reaction process participates in a strong interaction with the 2-oxo-3-pentenoate product, probably by the formation of a transient covalent bond, which in turn gives rise to in...