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Facile Preparation of (2Z,4E)-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate
Published on: June 21, 2017
Thermal isomerizations of 2-d-1-(E)-propenylcyclobutanes to 4-d-3-methylcyclohexenes
John E Baldwin1, Jean-Marie Fedé
1Department of Chemistry, Syracuse University, Syracuse, New York 13244, USA. jbaldwin@syr.edu
Abstract:
Racemic trans-2-d-1-(E)-propenylcyclobutane at 276 degrees C in the gas phase fragments to give ethylenes and pentadienes, equilibrates with its cis isomer, and rearranges to mixtures of 4-d- and 6-d-3-methylcyclohexenes through [1,3] carbon shifts. The time-dependent distributions of deuterium-labeled isomers of propenylcyclobutanes and 3-methylcyclohexenes reveal a significant secondary deuterium kinetic isotope effect favoring C1-C4 over C1-C2 bond breaking (kH/kD = 1.16 +/- 0.02) and a 72:28 preference for structural isomerizations giving (si + ar) rather than (sr + ai) products through conformationally flexible short-lived diradical intermediates.
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