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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 29, Number 6
BKCSDE 29(6)
June 20, 2008 

A Mechanistic Study on the Nucleophilic Addition Reactions of Benzylamines to the Activated Olefins
Hyuck Keun Oh
Nucleophilic addition reaction, Single-step process, Cross-interaction constant, Kinetic isotope effects, Four-center cyclic transition state
Kinetic studies of the additions of benzylamines to a noncyclic dicarbonyl group activated olefin, methyl α- acetyl-β -phenylacrylates (MAP), in acetonitrile at 30.0 oC are reported. The rates are lower than those for the cyclic dicarbonyl group activated olefins. The addition occurs in a single step with concurrent formation of the Cα-N and Cβ-H bonds through a four-center hydrogen bonded transition state. The kinetic isotope effects (kH/kD > 1.0) measured with deuterated benzylamines (XC6H4CH2ND2) increase with a stronger electron acceptor substituent (δσ X > 0) which is the same trend as those found for other dicarbonyl group activated series (1-4). The sign and magnitude of the cross-interaction constant, ρXY, is comparable to those for the normal bond formation processes in the SN2 and addition reactions. The relatively low ΔH≠ and large negative ΔS≠ values are also consistent with the mechanism proposed.
1195 - 1198
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