Synthesis of [3]Ferrocenophanes via Samarium Diiodide Promoted Reductive Cyclizations of 1,1‘-Dicinnamoylferrocenes

2000-06-01T00:00:00Z (GMT) by Shean-Jeng Jong Jim-Min Fang
A series of 1,1‘-dicinnamoylferrocenes were converted to the corresponding [3]ferrocenophane diols (<b>4a</b>−<b>e</b>) in a stereoselective manner by using samarium diiodide to effect the intramolecular coupling reaction, aldol reaction, and reduction in one-pot operation. The major reaction pathway might be derived from a samarium chelated transition state (<b>I</b><b><sub>A</sub></b>) having the moieties of<i> s</i>-<i>cis</i> enone and (<i>Z</i>)-enolate. A solid-state structure of such [3]ferrocenophane diol product showed that the cyclopentadienyl groups were in an eclipsed orientation and slightly tilted.