Synthesis 2006(15): 2503-2506  
DOI: 10.1055/s-2006-942454
PAPER
© Georg Thieme Verlag Stuttgart · New York

New Molecular Scaffolds: Synthesis of (2R,3R)- and (2S,3S)-3-Nitro-7-oxabicyclo[2.2.1]hept-5-ene-2-carbaldehyde from Furan

N. Araújo, María V. Gil, E. Román*, José A. Serrano
Departamento de Química Orgánica, Facultad de Ciencias, Universidad de Extremadura, 06071 Badajoz, Spain
Fax: +34(924)271149; e-Mail: roman@unex.es;
Further Information

Publication History

Received 16 February 2006
Publication Date:
11 July 2006 (online)

Abstract

Asymmetric Diels-Alder reactions between furan and chiral (E)-1,2-dideoxy-1-nitroalkenes derived from d-mannose and d-galactose take place quantitatively at room temperature and under high pressure (13 kbar), thus yielding, in each case, mixtures of the four possible stereoisomers of 3-nitro-2-(penta-O-acetylpentitol-1-yl)-7-oxabicyclo[2.2.1]hept-5-enes. The 3-nitro-7-oxabicyclo[2.2.1]hept-5-ene-2-carbaldehydes were obtained by deacetylation, followed by oxidative degration of the sugar chains of the corresponding major stereoisomers produced in each of the two Diels­-Alder reactions.

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These ratios were determined from the 1H NMR spectra of the mixtures, by integration of the signals corresponding to olefinic protons H-5 and H-6, or H-2, from each stereoisomer.