A low-temperature ammonium ylid rearrangement: enhanced reactivity engendered by rigidity
Sancon, J. and Sweeney, J.B. (2008) A low-temperature ammonium ylid rearrangement: enhanced reactivity engendered by rigidity. Synlett (14). pp. 2213-2214. ISSN 0936-5214
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To link to this article DOI: 10.1055/s-2008-1078256
Sigmatropic rearrangement of tetrahydropyridine-derived ammonium is a valuable method for the preparation of substituted prolines. These reaction normally require elevated temperatures to proceed, but bicyclic tetrahydropyridine-like ylid I undergoes rearrangement at -15 degrees C; the extra rigidity of the azabicyclo[3.3.0]octene system preorganizes the transition state and lowers the activation energy for rearrangement.