Acid-catalyzed aza-Diels-Alder versus 1,3-dipolar cycloadditions of methyl glyoxylate oxime with cyclopentadiene

• Type: Article in International Scientific Journal
• Date: 2008

Authors

Carlos A D Sousa (Author) Other; Luisa L C Vale (Author) FCUP; Jose E Rodriguez Borges (Author) FCUP; Xerardo Garcia Mera (Author) Other; Jesus Rodriguez Otero (Author) Other

Journal

Title: Tetrahedron Letters

Vol. 49

Pages: 5777-5781

ISSN: 0040-4039

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 19 Citations

Scopus - 21 Citations

Scientific classification

FOS: Natural sciences > Chemical sciences

Other information

Authenticus ID: P-003-W48

DOI: 10.1016/j.tetlet.2008.07.110

Abstract (EN): The acid-catalyzed 1,4- and 1,3-cycloadditions between methyl glyoxylate oxime (1) and cyclopentadiene were investigated using various Lewis and/or Bronsted acids at different temperatures in dichloromethane as solvent. Besides the expected new adducts, (+/-)-methyl [(3-exo)-2-hydroxy-2-azabicyclo[2.2.1]hept-5-ene]-3-carboxylate (2) and (+/-)-methyl [(3-endo)-2-hydroxy-2-azabicyclo[2.2.1]hept-5-ene]-3-carboxylate (3), a third adduct, (+/-)-methyl (1R,4R,5R)-(2-oxa-3-azabicyclo[3.3.0]oct-7-ene)-4-carboxylate (4), whose formation can be explained by a 1,3-dipolar cycloaddition, was obtained. Yields and product ratios were found to be more dependent on the catalyst than on the temperature; these results and the stereochemistry of the adducts, confirmed by spectroscopic data ((1)H and (13)C NMR) and by X-ray crystallography, were used to analyze and propose a mechanistic explanation for both cycloadditions.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 5