Highly Functionalised Cyclopentanes by Radical Cyclisation of Unsaturated Bromolactones III. Preparation of Carbaaldohexofuranoses. Determination of the Relative Configuration at C-4/C-5 of 2,3-Unsaturated Heptono-1,4-lactones by Means of 1H NMR Spectroscopy

Anne Marie Horneman; Inge Lundt

doi:10.1055/s-1999-3384

Synthesis 1999; 1999(2): 317-325
DOI: 10.1055/s-1999-3384

paper

© Georg Thieme Verlag, Rüdigerstr. 14, 70469 Stuttgart, Germany. All rights reserved. This journal, including all individual contributions and illustrations published therein, is legally protected by copyright for the duration of the copyright period. Any use, exploitation or commercialization outside the narrow limits set by copyright legislation, without the publisher's consent, is illegal and liable to criminal prosecution. This applies in particular to photostat reproduction, copying, cyclostyling, mimeographing or duplication of any kind, translating, preparation of microfilms, and electronic data processing and storage.

Highly Functionalised Cyclopentanes by Radical Cyclisation of Unsaturated Bromolactones III. Preparation of Carbaaldohexofuranoses. Determination of the Relative Configuration at C-4/C-5 of 2,3-Unsaturated Heptono-1,4-lactones by Means of ¹H NMR Spectroscopy

Anne Marie Horneman^* , Inge Lundt

^*Department of Organic Chemistry, Technical University of Denmark, Building 201, DK-2800 Lyngby, Denmark; Fax +45(45 93)39 68; E-mail: okil@pop.dtu.dk

Abstract

als PDF herunterladen Alle Artikel dieser Rubrik

Two new carbaaldohexofuranoses, carba-β-d-glucofuranose and carba-α-l-mannofuranose, have been prepared using 5,6-O-isopropylidene-d-glycero-l-galacto-heptono-1,4-lactone (6) as the starting material. The key step was a highly stereoselective intramolecular 5-exo-trig radical cyclisation of C-2 substituted 2,3-unsaturated 7-bromo-7-deoxyheptono-1,4-lactones promoted by tributyltin hydride. Assignment of the configuration of the unsaturated lactones was based upon NMR data of related compounds. The starting material, compound 6, was obtained by chain elongation of d-gulose, and a facile method for separation of the epimers from the chain elongation has been developed. Thus 5,6-O-isopropylidene-d-glycero-l-galacto-heptono-1,4-lactone (6) and d -glycero-l-talo-heptono-1,4-lactone (5) were isolated crystalline in ca. 30% and 10% yield, respectively.

carbasugars - radical cyclisation - bromoaldonolactones - 2,3-unsaturated 1,4-aldonolactones - heptonolactones

PDF (198 kb)