Researchers from Deakin University together with colleagues at the Freie Universitat,Berlin and Johannes Gutenberg Universitat,Mainz,Germany,have contributed to a fundamental improvement in understanding the unique properties of Grignard reagents prepared from chiral halides (Beckmann J.,Dakternieks D.,Drager M.,Duthie A.Angew.Chan.Int.Ed.Engl.2006,45,6509-12).Whereas previous literature suggested that the preparation of Grignard reagent from menthyl chloride proceeded with retention of configuration,their work emphasises that such reactions precede via a radical mechanism,resulting in a 1 :1 mixture of menthyl and neomenthyl Grignard reagents (see figure).Once formed,each component is conngurationally stable.Reaction with electrophiles yields products that are generally in accord with favoured attack by the more nucleophilic menthyl Grignard reagent,in which magnesium chloride occupies the equatorial position on the cyclohexyl ring.
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