Variable transition state structure in 3,3-sigmatropic shifts from. cap alpha. -secondary deuterium isotope effects

Journal Article · Wed Oct 24 00:00:00 EDT 1979 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00516a035· OSTI ID:5659646

Gajewski, J J; Conrad, N D

The relative values of secondary ..cap alpha.. deuterium kinetic isotopic effects at the terminal and central carbons of 1,5-dienes undergoing the 3,3-shifts vary as a function of substitution. With radical stabilizing groups on C/sub 3/, the transition state more resembles two weakly coupled allyl radicals. With radical stabilizing substituents at C/sub 2/ and C/sub 5/, the transition state more resembles cyclohexane-1,4-diyl. A thermochemical argument renders unlikely cyclohexane-1,4-diyl as an intermediate in the 3,3 shift of 1,5-hexadiene. Comparison of the KIEs at C/sub 4/ and C/sub 6/ in the rearrangement of 3-oxa-1,5-hexadiene (allyl vinyl ether to 4-pentenal) to appropriate equilibrium isotope effects reveals that the transition state comes early with more bond breaking than making. The transition state structures for many 3,3 shifts are discussed in terms of the relative stabilities of the two nonconcerted alternatives arising from either complete bond breaking or complete bond making. 50 references, 7 tables.

• Research Organization: Indiana Univ., Bloomington
• OSTI ID: 5659646
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 101:22; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301 -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
400302* -- Organic Chemistry-- Isotope Effects-- (-1987)
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
DATA
DATA FORMS
DECOMPOSITION
DEUTERIUM
DEUTERIUM COMPOUNDS
DIENES
ETHERS
EXPERIMENTAL DATA
HIGH TEMPERATURE
HYDROCARBONS
HYDROGEN COMPOUNDS
HYDROGEN ISOTOPES
INFORMATION
ISOLATED VALUES
ISOMERIZATION
ISOTOPE EFFECTS
ISOTOPES
LIGHT NUCLEI
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
POLYENES
PYROLYSIS
REACTION INTERMEDIATES
STABLE ISOTOPES
TEMPERATURE DEPENDENCE
THERMOCHEMICAL PROCESSES
YIELDS