: 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

The activation strain or distortion/interaction model is a tool to analyze activation barriers that determine reaction rates. For bimolecular reactions, the activation energies are the sum of the energies to distort the reactants into geometries they have in transition states plus the interaction energies between the two distorted molecules. The energy required to distort the molecules is called the activation strain or distortion energy. This energy is the principal contributor to the activation barrier. The transition state occurs when this activation strain is overcome by the stabilizing interaction energy. Following the changes in these energies along the reaction coordinate gives insights into the factors controlling reactivity. This model has been applied to reactions of all types in both organic and inorganic chemistry, including substitutions and eliminations, cycloadditions, and several types of organometallic reactions.

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Analyzing Reaction Rates with the Distortion/Interaction‐Activation Strain Model

Lung Wa Chung,† W. M. C. Sameera,‡ Romain Ramozzi,‡ Alister J. Page, Miho Hatanaka,‡ Galina P. Petrova, Travis V. Harris,‡,⊥ Xin Li, Zhuofeng Ke, Fengyi Liu, Hai-Bei Li, Lina Ding, and Keiji Morokuma*,‡ †Department of Chemistry, South University of Science and Technology of China, Shenzhen 518055, China ‡Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano Nishihiraki-cho, Sakyo, Kyoto 606-8103, Japan Newcastle Institute for Energy and Resources, The University of Newcastle, Callaghan 2308, Australia Faculty of Chemistry and Pharmacy, University of Sofia, Bulgaria Boulevard James Bourchier 1, 1164 Sofia, Bulgaria Department of Chemistry, State University of New York at Oswego, Oswego, New York 13126, United States State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275, China Key Laboratory of Macromolecular Science of Shaanxi Province, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an, Shaanxi 710119, China School of Ocean, Shandong University, Weihai 264209, China School of Pharmaceutical Sciences, Zhengzhou University, 100 Kexue Avenue, Zhengzhou, Henan 450001, China

The ONIOM Method and Its Applications

Recent Advances of Catalytic Asymmetric 1,3-Dipolar Cycloadditions

2.1. Oxygen Nucleophiles 3174 2.2. Nitrogen Nucleophiles 3177 3. Ag(I)-Mediated Addition of Nucleophiles to Allenes 3178 3.1. Oxygen Nucleophiles 3178 3.1.1. Allenic Alcohols 3178 3.1.2. Allenic Aldehydes and Ketones 3179 3.1.3. Allenic Acids 3180 3.2. Nitrogen Nucleophiles 3180 3.2.1. Allenic Amines 3180 3.2.2. Allenic Sulfonamides 3182 3.2.3. Allenic Carbamates 3182 3.2.4. Allenic Amides 3182 3.2.5. Allenic Oximes 3183 4. Ag(I)-Mediated Additions to Alkenes 3183 5. Ag(I)-Mediated Cycloaddition Reactions 3185 5.1. 1,3-Dipolar Cycloaddition Reactions of Azomethine Ylides 3185

Silver-mediated synthesis of heterocycles.

Synthesis of a Stable Disilyne Bisphosphine Adduct and Its Non‐Metal‐Mediated CO2 Reduction to CO

A wide range of new dipoles and catalysts have been used in 1,3-dipolar cycloadditions of N-metalated azomethine ylides onto C60 yielding a full stereodivergent synthesis of pyrrolidino[60]fullerenes with complete diastereoselectivities and very high enantioselectivities. The use of less-explored chiral α-iminoamides as starting 1,3-dipoles leads to an interesting double asymmetric induction resulting in a matching/mismatching effect depending upon the absolute configuration of the stereocenter in the starting α-iminoamide. An enantioselective process was also found in the retrocycloaddition reaction as revealed by mass spectrometry analysis on quasi-enantiomeric pyrrolidino[60]fullerenes. Theoretical DFT calculations are in very good agreement with the experimental data. On the basis of this agreement, a plausible reaction mechanism is proposed.

https://pubs.acs.org/doi/pdf/10.1021/ja410408c

Stereodivergent Synthesis of Chiral Fullerenes by [3 + 2] Cycloadditions to C60

Synthesis and Structure of a Base-Stabilized C-Phosphino-Si-Amino Silyne

Since the discovery of fullerenes and their further preparation on a multigram scale, these molecular carbon allotropes have been thoroughly investigated from the chemical viewpoint in the search for new modified fullerenes that are able to exhibit unconventional properties for practical applications. Furthermore, this knowledge has allowed a faster and better understanding of the chemical reactivity of the related carbon nanostructures, in particular of the promising carbon nanotubes, endohedral fullerenes, and the most recent graphenes. However, the number of studies on the reactivity of higher fullerenes is comparatively scarce and the use of asymmetric catalysis in these systems has been neglected so far. Higher fullerenes include a great diversity of molecules with different structures and chemical behavior that, because of the minor degree of symmetry, give rise to a complex covalent chemistry, in which chirality is an important and fascinating aspect. The preparation of chiral fullerenes has been based on chiral starting materials or, alternatively, on the most common racemic syntheses followed by complex, expensive, and highly time-consuming chromatographic isolation and purification processes. However, even when the isolation of the different isomers is feasible, the high costs and low abundance of higher fullerenes make necessary the availability of an efficient synthetic methodology to limit a broad distribution of products. Recently, we reported a straightforward procedure catalyzed by silver or copper acetate to efficiently obtain pyrrolidino[60]fullerenes with stereochemical control by enantioselective cycloaddition of azomethine ylides to the C60 molecule. [8] However, the extension of the scope of such a methodology to higher fullerenes, namely C70, is not a trivial process because C70 has to face many distinct levels of selectivity. Unlike C60, C70 lacks a spherical symmetry and has four different types of double bonds on the cage. The most common additions to [70]fullerene proceed in a 1,2 manner with a regioselectivity driven by the release of the strain of the double bond. Accordingly, additions occur preferentially at the most strained fullerene double bonds, namely those located at the polar zone (a site followed by b and g sites). The flatter equatorial region is less reactive and the addition only rarely takes place at the double bond of the d site. Particularly, cycloadditions of azomethine ylides typically give rise to the a, followed by the b, and a small amount of the g regioisomers (C(8) C(25), C(7) C(22), C(1) C(2) according to the systematic numbering; Figure 1). We propose to refer to these isomers (a, b, etc.) and to this form of selectivity as “site isomers” and site selectivity, respectively, to distinguish them from the regioisomers that result from the addition of nonsymmetric 1,3-dipoles to a double bond of the fullerene sphere. Indeed, depending on the orientation of the asymmetric azomethine ylide addition to the fullerene double bond, two regioisomers are, in turn, possible for each of the formed cycloadducts (see Figure 1). Furthermore, each of these regioisomeric pyrrolidines could be formed in a cis or trans configuration (diastereomers) and, in turn, in both of the enantiomeric forms. Herein we describe an efficient catalytic site-, regio-, diastereo-, and enantioselective cycloaddition of N-metalated azomethine ylides to C70 at low temperatures and while maintaining the atom economy principle. This methodology [*] E. E. Maroto, Dr. S. Filippone, Dr. . Mart n-Domenech, Prof. Dr. N. Mart n Departamento de Qu mica Org nica I Facultad de Ciencias Qu micas Ciudad Universitaria s/n, 28040 Madrid (Spain) Fax: (+ 34)91-394-4103 E-mail: nazmar@quim.ucm.es Homepage: http://www.ucm.es/info/fullerene

Hierarchical Selectivity in Fullerenes: Site‐, Regio‐, Diastereo‐, and Enantiocontrol of the 1,3‐Dipolar Cycloaddition to C70

(3 + 2) Cycloaddition reaction between azomethine ylides and π-deficient alkenes leads to densely substituted L- and D-unnatural prolines. These (3 + 2) cycloadducts in turn catalyse the preparation of an offspring of unnatural endo- and exo-L-proline derivatives. These latter compounds are also efficient catalysts of aldol reactions and yield aldol adducts with the opposite stereochemistry obtained under natural L-Pro organocatalysis.

Abel de Cózar

Papers

Synthesis of a Stable Disilyne Bisphosphine Adduct and Its Non‐Metal‐Mediated CO2 Reduction to CO

Stereodivergent Synthesis of Chiral Fullerenes by [3 + 2] Cycloadditions to C60

Synthesis and Structure of a Base-Stabilized C-Phosphino-Si-Amino Silyne

Hierarchical Selectivity in Fullerenes: Site‐, Regio‐, Diastereo‐, and Enantiocontrol of the 1,3‐Dipolar Cycloaddition to C70

Densely substituted unnatural L- and D-prolines as catalysts for highly enantioselective stereodivergent (3 + 2) cycloadditions and aldol reactions