Entropy-Controlled Asymmetric Synthesis. How Differential Activation Entropy Is Induced in Chiral Tethered Reactions
journal contributionposted on 07.12.2000, 00:00 by Takashi Sugimura, Kazutake Hagiya, Yasuhiro Sato, Takahiro Tei, Akira Tai, Tadashi Okuyama
Kinetic measurements to determine effective molarities of intramolecular reactions using 2,4-pentanediol and related tethers showed that methyl groups on the tether accelerate the major diastereomeric process but decelerate the minor process. The efficient promotion of stereocontrol is suggested to be due to chiral perturbation of the reaction rate through the entropy term. The conformation of the encounter complex of the reagent and reactant moieties was deduced by stereochemical analysis of the intramolecular adducts.
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reagenttetherInducedintramolecular adductstethersAsymmetricintramolecular reactionsdiastereomeric processChiral Tethered Reactions Kinetic measurementsmolaritieSynthesireactant moietiesconformationentropy termchiral perturbationpentanediolmethyl groupsencounterDifferential Activation Entropystereocontrolreaction ratestereochemical analysis