Stereospecificity in the ring-opening of ferrocenylcyclopropyl carbinols

✍ Scribed by William M. Horspool; Bruce J. Thomson

• Publisher: Elsevier Science
• Year: 1974
• Tongue: French
• Weight: 154 KB
• Volume: 15
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)91955-0

✦ Synopsis

Dehydration of the alcohol (la) to the olefin f3, So%> by a sulphuric acid-benzene system is accompanied by considerable decomposition of the starting material. A milder, more efficient dabydration was achieved by subjecting the same alcohol (la), as a ooncentrated ethereal solution, to chromatography on silica gel made up in petroleum ether. Under these conditions the mixture heats up as it is adsorbed onto the substrate. Continued elution with ether yields the olefin (3, 80%). The formation of the olefin probably results from the deprotonation of an intermediate a-ferrocenyl carbonium ion (3). The formation of a-ferrooenyl carbonium ions under such a system has support from the conversion of the sldohol into the ether (1~) by reflux of the alcohol in methanol with added silica @?l.