Enantiomerically Enriched Bicyclic Hydroxamic Acids in One Step from α-Aminohydroxamic Acids and Keto Acids via Cyclocondensation

Abstract

New enantiomerically enriched bicyclic hydroxamic acids, 1-hydroxy-dihydro-1H-pyrrolo[1,2-a]imidazole-2,5(3H,6H)-diones, have been synthesized by the cyclocondensation of L-α-aminohydroxamic acids with keto acids in a highly chemo- and stereoselective manner. The cis configuration between the amino acid side chain and the methyl group at C7a in 1H-pyrrolo[1,2-a]imidazole-2,5-dione was unambiguously established by X-ray crystallographic analysis. This method could also be applied to the cyclocondensation with o-formylbenzoic acid, giving a tricyclic hydroxamic acid in a good yield.

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GRAPHICAL ABSTRACT

Keywords:

• Chiral compounds
• cyclocondensation
• hydroxamic acids
• N-hydroxyimidazolidinones
• keto acids

ACKNOWLEDGMENTS

We are grateful to Nobuto Minowa (Meiji Seika Kaisha, Ltd.) for X-ray diffraction analysis of 3a. We also thank Seiichi Inoue (Yokohama National University, Japan) for his suggestions and valuable discussions. We are grateful to Nissan Chemical Industries, Ltd., for financial support.