Nicole Kunesch

Utilisation de la guanidine comme agent désacétylant sélectif:une méthode de désacétylation instantanée applicable aux sucres

Resume Guanidine efficiently and instantly deprotects a series of acetylatedcarbohydrates and phenols at room temperature. Phenolic acetates can be cleaved in the presence of benzylic acetates, while acetamides, benzoates and pivaloates remain stable.

Expeditious Enantioselective Biomimetic Synthesis of the Nitraria Alkaloids (+)‐Isonitramine and (−)‐Sibirine

The reaction of glutaraldehyde with (R)- or (S)-phenylglycinol as the source of nitrogen and the chirality inductor directly provides the spiropiperidine skeleton [Eq. (a)] of the alkaloids sibirine and isonitramine. The title compounds are available in a total of three and four steps, respectively.

Intramolecular Diels-Alder reaction of dinitro-olefin derivatives of furan for the preparation of a versatile tool: 3,7-dinitro-11-oxatricycloundec-9-ene

Recurrent additions of nitromethane on furfuraldehyde followed by an intramolecular Diels-Alder reaction allowed the obtention of the title compound 1 in good yield with excellent stereoselectivity. Aromatization, ether cleavage and stereocontrolled oxidation reactions give evidence of the synthetic versatility of this adduct in the preparation of ergot alkaloids and valienamine bicyclic analogues.

A simple total synthesis of both enantiomers of γ-amino-β-hydroxybutanoic acid (GABOB) by enzymatic kinetic resolution of cyanohydrin acetates

Abstract Both ( R )-and ( S )-3-cyano-e-hydroxy-propionic acid ethyl ester have been obtained via enzymatic kinetic resolution of the racemic acetate using lipase from Candida cylindracea and lipase from porcine pancreas respectively. Their selective reduction affords the corresponding ( R )-and ( S )-GABOB with high optical purity.

Synthesis of 2-dimethylaminoimidazole derivatives: a new access to indolyl-imidazole alkaloids of marine origin.

Abstract The first preparation of 2-dimethylaminoimidazole 1a , a structural feature of several marine products was undertaken and its reactivity investigated. The synthesis of natural alkaloids 5 and 12b was achieved by direct coupling of the easily accessible oxidized 2-dimethylaminoimidazoles 7 and 8 with indole-3-carboxaldehyde and indole respectively, demonstrating the usefulness of this approach for other structurally related natural products.

Neoflavonoids from the stem bark of Calophyllum verticillatum

Abstract The chemical investigation of the extractives of Calophyllum verticillatum provided three new neoflavonoids: caloverticillic acids A, B and C, in addition to α-amyrin and friedelin. Molluscicidal activity against Biomphalaria glabrata was observed.

L'isopolyalthenol et le neopolyalthenol, nouveaux indolosesquiterpenes isolés de Polyalthia suaveolens, annonacees

Abstract The novel indolosesquiterpenes isopolyalthenol 3 and neopolyalthenol 4 have been obtained from Polyalthia suaveolens (Annonaceae). A pathway for the biogenesis of indolosesquiterpenes is considered.

A simple total synthesis of (S)-isoserine

Abstract Kinetic enzymatic resolution by Candida cylindracea lipase of racemic isoserine diacetate prepared from the cyanohydrin of glyoxylate provided ( S )-isoserine in good yield and high optical purity.

Isolation and structure determination of a new sesquiterpene lactone from Nauplius aquaticus.

Abstract The aerial part of Nauplius aquaticus afforded a new sesquiterpene lactone with a humulanolide skeleton, 6,7,9,10-tetrahydroasteriscunolide (1), in addition to the known asteriscunolides A (2) and D (3). Their structures were established principally by two-dimensional NMR spectroscopy.

Einfache enantioselektive biomimetische Synthese der Nitraria‐Alkaloide (+)‐Isonitramin und (−)‐Sibirin

Die Umsetzung von Glutaraldehyd mit (R)- oder (S)-Phenylglycinol als Stickstoffquelle und Chiralitatsinduktor ergibt direkt das Spiropiperidingerust [Gl. (a)] der Alkaloide Sibirin und Isonitramin. Mit insgesamt nur drei bzw. vier Schritten kommt man zu den Zielverbindungen.