Acta Crystallographica Section C

Crystal Structure Communications

Volume 60, Part 9 (September 2004)

fr1490 scheme

Acta Cryst. (2004). C60, o656-o658 [doi:10.1107/S0108270104015951]

Preference for the Diels-Alder addition of dienes syn to the O atom in cross-conjugated spirocyclic cyclohexadienones

J. C. Gallucci, Y. Tamura and L. A. Paquette

Abstract: In the Diels-Alder reaction, the preferred addition of dienes syn to the O atom in cross-conjugated cyclohexadienones containing an oxa-spiro ring system is observed. The two structures reported here, namely rel-(1R,4aR,9S,9aS,10R)-4a,9,9a,10-tetrahydro-9,10-diphenylspiro[9,10-epoxyanthracene-1(4H),2'-oxiran]-4-one, C₂₇H₂₀O₃, and rel-(1R,4aS,9R,9aS,10S)-4a,9,9a,10-tetrahydro-9,10-diphenylspiro[9,10-epoxyanthracene-1(4H),2'-oxetane]-4-one, C₂₈H₂₂O₃, are the minor and sole products, respectively, of the reactions of diphenylisobenzofuran with two slightly different cyclohexadienones. These structures differ in the size of the oxa-spiro ring, by one C atom, and in the relative configuration at the spirocyclic ring C atom, leading to some minor conformational differences between the two compounds.

Formula: C₂₇H₂₀O₃ and C₂₈H₂₂O₃

Online 11 August 2004


	Structure factor file (CIF format) (219.2 kbytes) Contains datablock III

	Structure factor file (CIF format) (225.8 kbytes) Contains datablock IV

Notes:

To open or display or play some files, you may need to set your browser up to use the appropriate software. See the full list of file types for an explanation of the different file types and their related mime types and, where available links to sites from where the appropriate software may be obtained.

The download button will force most browsers to prompt for a file name to store the data on your hard disk.

Where possible, images are represented by thumbnails.