Synthesis 2009(19): 3259-3262  
DOI: 10.1055/s-0029-1216934
PAPER
© Georg Thieme Verlag Stuttgart ˙ New York

Copper(I)-Promoted Synthesis of 4-Oxaspiro[2.4]hepta-1,6-dien-5-ones from Cyclopropenones

Olivia Körner, Rolf Gleiter*, Frank Rominger
Organisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
Fax: 06221/544205; e-Mail: rolf.gleiter@oci.uni-heidelberg.de;
Further Information

Publication History

Received 10 March 2009
Publication Date:
14 August 2009 (online)

Abstract

Heating of dialkyl- or diarylcyclopropenones at 75 ˚C in the presence of copper(I) bromide (5 mol%) affords the corresponding 4-oxaspiro[2.4]hepta-1,6-dien-5-ones in good yields.

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X-ray crystal structure of spirolactone 2a: colorless crystals, dimensions 0.43 × 0.24 × 0.12 mm³, crystal system triclinic, space group P 1, Z = 4, a = 9.8710 (7) Å, b = 13.9125 (10) Å, c = 17.8257 (13) Å, α = 112.166 (2)˚, β = 93.589 (2)˚, γ = 99.743 (2)˚, V = 2212.8 (3) ų, ρ = 1.24 g/cm³, T = 200(2) K, Θmax = 28.41˚, radiation MoKα, λ = 0.71073 Å, 0.3˚ ω-scans with CCD area detector on a Bruker APEX diffractometer, covering a whole sphere in reciprocal space, 23425 reflections measured, 10943 unique [R(int) = 0.0315], 8256 observed [I ≤ 2σ(I)], µ = 0.076 mm, T max = 0.99, T min = 0.97, 577 parameters refined, hydrogen atoms were treated using appropriate riding models, goodness of fit 1.15 for observed reflections, final residual values R1 (F) = 0.071 and wR(F ²) = 0.136 for observed reflections, residual electron density -0.28 to 0.23 eÅ. CCDC 723391 (2a) contains the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.

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X-ray crystal structure of spirolactone 2d: colorless crystals, dimensions 0.41 × 0.22 × 0.20 mm³, crystal system monoclinic, space group P21/c, Z = 4, a = 8.8717 (7) Å, b = 14.8246 (12) Å, c = 9.8321 (8) Å, β = 93.498 (2)˚, V = 1290.70 (18) ų, ρ = 1.26 g/cm³, T = 200(2) K, Θmax = 28.29˚, radiation MoKα, λ = 0.71073 Å, 0.3˚ ω-scans with CCD area detector on a Bruker APEX diffractometer, covering a whole sphere in reciprocal space, 13318 reflections measured, 3194 unique [R(int) = 0.0238], 2886 observed [I ≤ 2σ(I)], µ = 0.081 mm, T max = 0.98, T min = 0.97, 163 parameters refined, hydrogen atoms were treated using appropriate riding models, goodness of fit 1.08 for observed reflections, final residual values R1 (F) = 0.050 and wR(F ²) = 0.123 for observed reflections, residual electron density -0.16 to 0.33 eÅ. CCDC 723392 (2d) contains the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.