Chiral Rare Earth Metal Complex‐Catalyzed Conjugate Addition of O‐Alkylhydroxylamines. An Efficient Synthetic Entry into Optically Active 2‐Acyl Aziridines.

Abstract

Active 2-Acyl Aziridines. -Conjugate addition of O-alkylhydroxylamines (II) and (VI) to α,β-unsaturated ketones (I) and (V) in the presence of a chiral scandium-BINOL-derived phosphate complex represents a novel efficient approach to the synthesis of enantiopure β-alkoxamino ketones (III) and (VII), respectively. Base-mediated elimination then proceeds without racemization and in almost quantitative yields to furnish optically active 2-acylaziridines [cf. (IV)]. A remarkably high asymmetric amplification is observed in the conjugate addition reaction. Additionally, it is shown that the elimination reaction of racemic β-methoxamino ketone (III) in the presence of La-chiral BINOL complex proceeds with kinetic resolution. -(JIN, X. L.; SUGIHARA, H.; DAIKAI, K.; TATEISHI, H.; JIN, Y. Z.; FURUNO, H.; INANAGA*, J.; Tetrahedron 58 (2002) 41, 8321-8329; Inst. Fundam. Res. Org. Chem., Kyushu Univ., Hakozaki, Fukuoka 812, Japan; Eng.) -Mischke 10-105 2002 Aziridine derivatives

Asymmetric Catalysis and Amplification with Chiral Lanthanide Complexes

“…74 Recently, we found that the Sc[(R)-BNP] 3 complex (Sc-4) was a quite effective catalyst for the addition reaction of nitrogen nucleophiles to conjugated enones; the enantioselective addition reaction of O-diphenylmethylhydroxylamine to various conjugated enones was accomplished at room temperature with almost complete enantioselectivities (up to >99% ee) (Scheme 25), and as shown in Figure 10, a significant asymmetric amplification was observed in this reaction. 75 The Michael adducts thus obtained can be cleanly converted to the corresponding R-keto aziridines by catalysis with NaO-t-Bu or La(O-i-Pr) 3 .…”