A general strategy for the amino acid homologation via Blaise reaction and subsequent reduction is presented. This strategy involves the preparation of protected alpha-amino nitriles from the corresponding amino acids, followed by the zinc-mediated condensation of tert-butyl bromoacetate, to give the imidazolidones after iminozincate cyclization. Reduction gave the saturated imidazolidinones with cis or trans stereochemistry, depending on the reduction conditions. This strategy was applied to nonfunctionalized amino acids and to functionalized amino acids such as serine and aspartic acid. Additionally, acidic hydrolysis of cis or trans imidazolidinones to the corresponding chiral 4-aminopyrrolidones is described.

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Alkyl nitrones possessing N-substituted sugars as chiral auxiliaries were found to effectively undergo an SmI(2)-mediated radical addition to n-butyl acrylate affording gamma-amino acid derivatives with high diastereomeric control.

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X-ray and NMR experiments were performed with simple chitosan models based on glucosamine monosaccharides and disaccharides to understand the binding properties and structures of the complexes formed between this polysaccharide and platinum(II) metals. Subjection of the glucosamine derivatives with [PdCl2(PhCN)2] provided trans-diamine complexes which upon further treatment with excess (NH4)PF6 generated complexes possessing two 5-membered chelate rings involving the C2-amine and the C3-hydroxyl group of the two individual glucosamine units.

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Imidazole derivatives R 0190Amino Acid Homologation by the Blaise Reaction: A New Entry into Nitrogen Heterocycles. -Treatment of Cbz-protected amino nitriles of type (IV) derived from α-amino acids with bromoacetate and subsequent base-mediated cyclization provides a new approach to imidazolidinones like (VI). These compounds smoothly undergo stereoselective reduction to give cis-and/or trans-substituted imidazolidinones. Hydrolysis of the latter does not yield the expected β,γ-diamino acids but cyclization products like (IX) and (X). Blaise reaction of the functionalized amino nitrile (XIII) provides the lactam (XIV) instead of the corresponding imidazolidinone. (XIV) undergoes stereoselective reduction giving the trans-substituted lactam (XV). -(HOANG, C. T.; BOUILLERE, F.; JOHANNESEN, S.; ZULAUF, A.; PANEL, C.; POUILHES, A.; GORI, D.; ALEZRA*, V.; KOUKLOVSKY, C.; J.

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