6-Endo-trig mode cyclization to a hydrindanone using samarium (II) iodide

Abstract

Samarium(II) iodide has been employed to promote the vinylogous pinacol coupling reaction of aldehyde to α, β-unsaturated ketones. The diastereoselectivity of 6-endo-trig mode products was changed by the addition of a proton source and/or HMPA and by the reaction temperature. The stereochemistry of the hydrindanone was controlled by the coordinated samarium species, resulting in the cis-orientation in respect of the hydroxyl group at C-4 and the juncture proton at C-3a under mild reaction conditions. Coronafacic acid has been synthesized from a hydrindanone prepared by the cyclization reaction of the enone-aldehyde with samarium(II) iodide. © 2003 The Pharmaceutical Society of Japan.