Synlett 2008(2): 197-202  
DOI: 10.1055/s-2007-1000934
LETTER
© Georg Thieme Verlag Stuttgart · New York

Formal Mixed Double Addition to N-Glycosylnitrones through Addition-Oxidation-Addition to N-Glycosylhydroxylamines

Marco Bonanni, Marco Marradi, Stefano Cicchi, Andrea Goti*
Dipartimento di Chimica Organica ‘Ugo Schiff’, HeteroBioLab, Università di Firenze, associated with INSTM and ICCOM-C.N.R., via della Lastruccia 13, 50019 Sesto Fiorentino (FI), Italy
Fax: +39(055)4573531; e-Mail: andrea.goti@unifi.it;
Further Information

Publication History

Received 2 November 2007
Publication Date:
21 December 2007 (online)

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Abstract

A protocol for the formal mixed addition of two different C-nucleophiles at C1 and C1′ of N-glycosylnitrones has been developed. Addition of Grignard reagents to N-erythrosyl-N-benzylhydroxylamine 1 affords hydroxylamines 6 almost quantitatively with high diastereoselectivity. These compounds undergo regioselective oxidation to the corresponding C-phenyl nitrones 7, which in turn add a second Grignard reagent to give hydroxylamines 5. Synthetic usefulness of mixed bisadduct 5d has been proved by its enyne ring-closing metathesis to afford the densely functionalized unsaturated piperidine derivative 8.