: The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

Iron Catalysis in Organic Synthesis

Organic Chemistry By Dr. I. L. Finar. Vol. 2: Stereochemistry and the Chemistry of Natural Products. Pp. xi + 733. (London and New York: Longmans, Green and Co., Ltd., 1956.) 40s. net.

Advanced Organic Chemistry

Two-dimensionally extended, polycyclic heteroaromatic molecules (heterocyclic nanographenes) are a highly versatile class of organic materials, applicable as functional chromophores and organic semiconductors. In this Review, we discuss the rich chemistry of large heteroaromatics, focusing on their synthesis, electronic properties, and applications in materials science. This Review summarizes the historical development and current state of the art in this rapidly expanding field of research, which has become one of the key exploration areas of modern heterocyclic chemistry.

Heterocyclic Nanographenes and Other Polycyclic Heteroaromatic Compounds: Synthetic Routes, Properties, and Applications

Trifluoromethyltrimethylsilane: nucleophilic trifluoromethylation and beyond.

Contemporary Carbocation Chemistry: Applications in Organic Synthesis

3,3-Diaryloxidoles are prepared in high yields (62−99%) by reaction of isatin or substituted isatins with aromatics in triflic acid. The reaction shows a significant dependence on acid strength which suggests the formation of diprotonated, superelectrophilic intermediates. Reaction of isatin, benzene, and acid systems of varying strength (composed of CF3SO3H and CF3CO2H) showed that the acid strength must be more acidic than Ho = −11.5 for complete conversion to product. Reaction of isatins with mixtures of aromatics allows for the preparation of libraries of 3,3-diaryloxindole products by combinatorial synthesis.

Preparation of 3,3-Diaryloxindoles by Superacid-Induced Condensations of Isatins and Aromatics with a Combinatorial Approach

Preface. 1. General Aspects. 2. Study of Superelectrophiles. 3. Generating Superelectrophiles. 4. Gitonic Geminal Superelectrophiles. 5. Gitonic Vicinal Superelectrophiles. 6. Gitonic 1,3-Superelectrophiles. 7. Distonic Superelectrophiles. 8. Significance and Outlook. Index.

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Superelectrophiles and Their Chemistry

The chemistry of cinnamic acids and related compounds has been studied. In superacid-catalyzed reactions with arenes, two competing reaction mechanisms are proposed. Both mechanisms involve the formation of dicationic intermediates (superelectrophiles), and the reactions can lead to either chalcone-type products or indanone products. The direct observation of a dicationic species (by low-temperature (13)C NMR) is reported. We provide clear evidence that protonated carboxylic acid groups (or the corresponding acyl cation) can enhance the reactivity of an adjacent electrophilic center. Triflic acid is also found to be an effective acid catalyst for the direct synthesis of some electron-deficient chalcones and heterocyclic chalcones from cinnnamic acids.

Superacid-catalyzed reactions of cinnamic acids and the role of superelectrophiles.

The superacid-promoted reactions of alpha-hydroxy and alpha-ketoamides have been studied. Ionization of these compounds leads to varied aryl-substituted oxyindole products. In some cases, electrocyclization can lead to substituted fluorene products. Dicationic, superelectrophilic intermediates are proposed as intermediates leading to the products from alpha-hydroxy and alpha-ketoamides.

Douglas A. Klumpp

Papers

Contemporary Carbocation Chemistry: Applications in Organic Synthesis

Preparation of 3,3-Diaryloxindoles by Superacid-Induced Condensations of Isatins and Aromatics with a Combinatorial Approach

Superelectrophiles and Their Chemistry

Superacid-catalyzed reactions of cinnamic acids and the role of superelectrophiles.

Superacid-Promoted Reactions of α-Ketoamides and Related Systems