Preparative Organic Chemistry
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ChemInform Abstract: Exclusion of a 1,4-Cyclohexenediyl as a Metastable Intermediate in the (3,3) Sigmatropic Rearrangement of a 1-Hexen-5-yne.
First published: May 3, 1988
Abstract
From a detailed product examination after 2 and 6 half-lives it is deduced that the (3,3) sigmatropic rearrangement of (-)-(S,E)-(I) (62.2 ±2% ee) at 200 °C to (Z)- and (E)-(I), (Z)- and (E)-(III), and other materials proceed with near-perfect preservation of enantiomeric purity, the "allowed" pathway being favored.
ChemInform Abstract
From a detailed product examination after 2 and 6 half-lives it is deduced that the (3,3) sigmatropic rearrangement of (-)-(S,E)-(I) (62.2 ±2% ee) at 200 °C to (Z)- and (E)-(I), (Z)- and (E)-(III), and other materials proceed with near-perfect preservation of enantiomeric purity, the "allowed" pathway being favored. The experiments permit the much discussed diyl radical (II) to be a transition state but not a true intermediate.
