Hypervalent Iodine Oxidants: Structure and Kinetics of the Reactive Intermediates in the Oxidation of Alcohols and 1,2-Diols by o-Iodoxybenzoic Acid (IBX) and Dess−Martin Periodinane. A Comparative 1H-NMR Study
摘要:
Alcohols and 1,2-diols oxidation by o-iodoxybenzoic acid (IBX) has been examined by H-1-NMR spectroscopy. Reversible formation of reactive intermediates, iodic esters 5, has been observed, and their structures in DMSO-d(6) solution have been defined as 10-I-4 axial alkoxyiodinane oxides by comparison of the chemical shift difference data with those obtained for Dess-Martin periodinane (DMP)-alcoholate and -diolate adducts. The dichotomous behavior exhibited by IBX and DMP with 1,2-diols can be explained in terms of the different architecture of the reactive intermediates involved in the oxidation. With aliphatic alcohols, kinetic evidences support a two-step reaction mechanism involving a fast pre-equilibrium step leading to 5, followed by a rate-determining disproportionation step. With electronically activated benzyl alcohol, the attainment of preequilibrium is largely dependent on initial water concentration as a consequence of a particularly high k(2) value. The influence of the alcohol structure on measured equilibrium (K-eq) and rate constants (k(2)) and the effect of water on the overall reaction rate are discussed.
Hypervalent Iodine Oxidants: Structure and Kinetics of the Reactive Intermediates in the Oxidation of Alcohols and 1,2-Diols by o-Iodoxybenzoic Acid (IBX) and Dess−Martin Periodinane. A Comparative 1H-NMR Study
摘要:
Alcohols and 1,2-diols oxidation by o-iodoxybenzoic acid (IBX) has been examined by H-1-NMR spectroscopy. Reversible formation of reactive intermediates, iodic esters 5, has been observed, and their structures in DMSO-d(6) solution have been defined as 10-I-4 axial alkoxyiodinane oxides by comparison of the chemical shift difference data with those obtained for Dess-Martin periodinane (DMP)-alcoholate and -diolate adducts. The dichotomous behavior exhibited by IBX and DMP with 1,2-diols can be explained in terms of the different architecture of the reactive intermediates involved in the oxidation. With aliphatic alcohols, kinetic evidences support a two-step reaction mechanism involving a fast pre-equilibrium step leading to 5, followed by a rate-determining disproportionation step. With electronically activated benzyl alcohol, the attainment of preequilibrium is largely dependent on initial water concentration as a consequence of a particularly high k(2) value. The influence of the alcohol structure on measured equilibrium (K-eq) and rate constants (k(2)) and the effect of water on the overall reaction rate are discussed.
A heterocycle-containing aromatic compound represented by the formula: A-B, and an electrically conductive polymer obtained by oxidative polymerization of the heterocycle-containing aromatic compound as a monomer are provided. In the above formula, A represents a substituted or unsubstituted thiophene ring group, or a substituted or unsubstituted pyrrole ring group; B represents a substituted or unsubstituted hydrocarbon aromatic ring group, a substituted or unsubstituted thiophene ring group, or a substituted or unsubstituted pyrrole ring group; the ring represented by A and the ring represented by B are directly linked; however, A and B represent structures that are different from each other. The compound can be produced by a coupling reaction using a hypervalent iodine reactant.
Acceleration of the Dess-Martin Oxidation by Water
作者:Stephanie D. Meyer、Stuart L. Schreiber
DOI:10.1021/jo00103a067
日期:1994.12
Dess, Daniel B.; Martin, Journal of the American Chemical Society, 1991, vol. 113, # 19, p. 7277 - 7287
作者:Dess, Daniel B.、Martin
DOI:——
日期:——
Hypervalent Iodine Oxidants: Structure and Kinetics of the Reactive Intermediates in the Oxidation of Alcohols and 1,2-Diols by <i>o</i>-Iodoxybenzoic Acid (IBX) and Dess−Martin Periodinane. A Comparative <sup>1</sup>H-NMR Study
作者:Sergio De Munari、Marco Frigerio、Marco Santagostino
DOI:10.1021/jo961044m
日期:1996.1.1
Alcohols and 1,2-diols oxidation by o-iodoxybenzoic acid (IBX) has been examined by H-1-NMR spectroscopy. Reversible formation of reactive intermediates, iodic esters 5, has been observed, and their structures in DMSO-d(6) solution have been defined as 10-I-4 axial alkoxyiodinane oxides by comparison of the chemical shift difference data with those obtained for Dess-Martin periodinane (DMP)-alcoholate and -diolate adducts. The dichotomous behavior exhibited by IBX and DMP with 1,2-diols can be explained in terms of the different architecture of the reactive intermediates involved in the oxidation. With aliphatic alcohols, kinetic evidences support a two-step reaction mechanism involving a fast pre-equilibrium step leading to 5, followed by a rate-determining disproportionation step. With electronically activated benzyl alcohol, the attainment of preequilibrium is largely dependent on initial water concentration as a consequence of a particularly high k(2) value. The influence of the alcohol structure on measured equilibrium (K-eq) and rate constants (k(2)) and the effect of water on the overall reaction rate are discussed.