Organobase catalysed one-pot exo-selective synthesis of meso-spiro[cyclohexanone-pyrandione] derivatives. (31st August 2017)

• Record Type: Journal Article
• Authors: Talhi, Oualid; Abdeldjebar, Hasnia; Belmiloud, Yamina; Hassaine, Ridha; Taibi, Nadia; Válega, Mónica; Paz, Filipe A. A.; Brahimi, Meziane; Bachari, Khaldoun; Silva, Artur M. S.
• Is Part Of: New journal of chemistry. Volume 41:Number 19(2017)
• Page Start: 10790
• Page End: 10798
• Publication Date: 2017-08-31
• Subjects: Chemistry -- Periodicals; Chimie -- Périodiques; 540
• DOI: 10.1039/c7nj02168b
• Languages: English
• ISSNs: 1144-0546

Abstract

Abstract : A facile metal-free one-pot exo -stereoselective synthesis of through two sequential organobase-catalysed 1, 4-conjugate additions of pyran-2, 4-diones on diarylideneacetone synthons is disclosed. Abstract : An exo -selective one-pot synthesis of novel spiro[cyclohexanone-pyrandione] derivatives through two sequential organobase-catalysed 1, 4-conjugate additions of pyran-2, 4-dione precursors on diarylideneacetone derivatives is described. The resulting 7, 11-diaryl-2-oxaspiro[5.5]undec-3-ene-1, 5, 9-triones were obtained as a 2 : 1 mixture of exo - and endo -diastereomers and adopt a meso -form due to the bilateral symmetry existing in the scaffold. Chiral-HPLC, NMR and single-crystal X-ray diffraction (including synchrotron data) have been used to elucidate the spiro[cyclohexanone-pyrandione] structure, showing therefore the exo / endo -diastereomers obtained in a meso -form, the cis -7, 11-diaryl configuration (equatorial position) and different conformational changes in the cyclohexanone skeleton both in liquid and solid states. DFT studies proved the exo -stereoselectivity of the reaction by determining the exo / cis equatorial–equatorial configuration as the most thermodynamically stable form of our spiro[cyclohexanone-pyrandione] skeleton, while the structural substitution has no effect.