Crystallization-induced asymmetric transformation. Application to conjugate addition of benzylamine to amides of benzoylacrylic acid

Adducts of the conjugate addition of benzylamine to enantiopure amides of aroylacrylic acid possess high enantiomeric and diastereomeric purity. A high degree of stereoselectivity has been achieved by means of crystallization-induced asymmetric transformation. A practical synthesis leading to dipeptides containing homophenylalanine is depicted.     

Valency. II. Applications to molecules with first-row atoms

A quantum chemical definition of valency proposed in Part I is used to calculate the valency of carbon, nitrogen, oxygen, lithium, beryllium and boron in a number of compounds with the SINDO1 method. It is demonstrated that consistency of the basis set is necessary for comparable results. The general features of valency and bonding in these molecules are discussed. The π-electron concept of free valence is generalised to sigma systems and atoms in molecules are classified as subvalent, normal or hypervalent. The relation between valency and natural hybrid occupancy is illustrated. The symmetry properties of natural hybrid orbitals are discussed by means of group theory. A preliminary attempt is made to relate covalency and covalent reactivity. Bond indices and the σ, π character of bonds are obtained by a suitable partitioning and projection of valency into bonding and antibonding contributions. Alexander von Humboldt Fellow 1982–83.     

A three-component coupling approach to cyclopentanoids.

A new approach to 2,3-disubstituted cyclopentenones has been developed. This approach consists of a two-step protocol involving the cyclization of a Z-vinyl bromide under Barbier type conditions to form a cyclopentenol, which is then oxidatively rearranged to generate the cyclopentenone. The Z-vinyl bromide is in turn derived from a ruthenium catalyzed three-component coupling of an alkyne, an enone, and a HBr equivalent. A range of 2,3-disubstituted cyclopentenones has been generated, including short syntheses of jasmone and dihydrojasmone. Further applicability of this strategy is shown in the total syntheses of tetrahydrodicranenone B, rosaprostol, and a selective COX-2 inhibitor.     

Organopalladium approaches to prostaglandins. 2. Synthesis of prostaglandin endoperoxide analogs via π-allylpalladium additions to bicyclic olefins

A variety of prostaglandin endoperoxide analogos are readily available by addition of π-allylpalladium compounds to bicyclic olefins and subsequent treatment with alkenyl and alkynyl organometallics. Pronounced biological activity is evident in these compounds.     

J. J. Thomson goes to America

Joseph John (J. J.) Thomson was an accomplished scientist who helped lay the foundations of nuclear physics. A humble man of working class roots, Thomson went on to become one of the most influential physicists of the late 19th century. He is credited with the discovery of the electron, received a Nobel Prize in physics in 1906 for investigations into the conduction of electricity by gases, was knighted in 1908, and served as a Cavendish Professor and Director of the laboratory for over 35 years from 1884. His laboratory attracted some of the world’s brightest minds; Francis W. Aston, Niels H. D. Bohr, Hugh L. Callendar, Charles T. R. Wilson, Ernest Rutherford, George F. C. Searle, Geoffrey I. Taylor, and John S. E. Townsend all worked under him. This article recounts J. J. Thomson’s visits to North America in 1896, 1903, 1909, and finally 1923. It presents his activities and his personal impressions of the people and society of the U.S.A. and Canada, and the science of atomic physics and chemistry in the late 1800s and early 1900s.     

Application of mass spectrometry to the study of fluoropolymers. III. Polyperfluorobut-2-yne

Mass spectra of the volatile fractions from polyperfluorobut-2-yne have been obtained. The polymer appears to be thermally stable up to 300°C and molecules containing up to 12 monomer units have been identified. A regular structure is indicated by the mass spectrum which is characterized by unusually intense doubly charged ions. The endgroups are readily identified, and a conjugated polyolefin structure is indicated.     

Synthetic quinine,analogs. V. Quinolinemethanols related to desvinylquinine

Aldol condensation of quinolinecarboxaldehydes with 3-quinuelidinone followed by acid-catalyzed hydration of the resulting α,β-unsalurated ketones provides a short and versatile synthesis of desvinylquinine derivatives. A novel rearrangement of 2-(9-phenanthrylmethylene)-3-quinuclidinyl earbinols leading to dibenzoindole derivatives is described.     

Lipase-Mediated Acylation of Acyclonucleosides. Application to Novel Fluoroquinolone Derivatives

A novel kind of acyclonucleoside derived from fluoroquinolones is described. Lipases have been used to prepare acyl derivatives under mild conditions and in good yields.     

Benzomorphan related compounds. II. New synthesis route to thienomorphans

A new synthesis route to α-2,5,9-trimethylthieno[3,2-f]morphan and two analogous compounds from cyanopyridines and 2-thienyllithium is described. Spectroscopic data of these substances and their intermediates are included.     

Topological organic chemistry. 13. Transformation of graph adjacency matrixes to distance matrixes

A sequence of simple arithmetic operations is described that generates distance matrixes from the adjacency matrixes of graphs.     

Enantioselective Michael reactions. Stereoselective addition of enolates of phenmenthol esters to crotonates

A method is described for enantioselective synthesis which is based on the stereoselective Michael addition of phenmenthol enolates such as 5 to $\text{E}$-crotonate esters. A stereomechanistic rationale is presented.     

Isoprenic thiovinylcarbenes. 2. Intermolecular reactions with olefins,dienes and acetylenes. Direct access to chrysanthemic esters.

The isoprenic thiovinylcarbene formed by photolysis of gem-dimethyl-5-ethylthiopyrazolenine shows a surprisingly good intermolecular reactivity toward electrophilic olefins and acetylenes. A direct access to chrysanthemic esters is thus provided.     

Extended hydrodynamic approach to quantum-classical nonequilibrium evolution. II. Application to nonpolar solvation

The mixed quantum-classical formulation derived in our companion paper [D. Bousquet, K. H. Hughes, D. Micha, and I. Burghardt, J. Chem. Phys. 134, 064116 (2011)], which is based upon a hydrodynamic representation of the classical sector, is applied to nonequilibrium nonpolar solvation dynamics as exemplified by the solvation of the electronically excited NO molecule in a rare gas environment. Derived from a partition of the Hamiltonian into a primary (quantum) part and a secondary (classical) part the hydrodynamic equations are formulated for multi-quantum states and result in explicit equations of motion for populations and coherences. The hierarchy of hydrodynamic equations is truncated by the following approximate closure schemes: Gauss-Hermite closure, dynamical density functional theory approximation, and a generalized Maxwellian closure. A comparison of the dynamics using these three closure methods showed that the suitability of a particular closure scheme was dependent on the initial conditions and the nonequilibrium character of the dynamics.     

A relay approach to (+)-pleuromutilin. II. preparation of an advanced optically pure intermediate

A four-step degradation of (+)-pleuromutilin (1a) to levorotatory lactone 5 is detailed. The conversion of 5 into (-)-bicyclic diketone 9, an intermediate containing all 20 carbon atoms of the target molecule, is also described.     

Harmonic oscillator tensors. IV. A tensorial approach to internal rotations in molecules

A mapping of 2×2 matrices into the space of single boson operators is shown to lead to the angular momentum operators that give rise to irreducible tensors for the harmonic oscillator. The mapping may also be used to define an axis of quantization. A rotation about this axis induces a wave function and Hamiltonian that may be applied to the study of internal rotations in molecules. The example of a molecule containing two coaxial symmetric tops is presented as a case in point. The case of a potential with a high barrier leads to the approximation of an internal rotation as a torsional oscillator and, consequently, to torsional oscillator tensors whose properties are the same as those of the harmonic oscillator. The possibility of studying more complex potentials is discussed. © 1997 John Wiley & Sons, Inc. Int J Quant Chem 65 : 305–315, 1997     

Analysis of benzodiazepines. II. High-performance liquid chromatography-fluorescence detection after molecular rearrangement to acridanones

A molecular rearrangement of benzophenones (hydrolysis products of 1,4-benzodiazepines) to 9-acridones has been studied. The compounds synthesized were analysed by high-performance liquid chromatography coupled with a fluorescence detector, because of their high luminescence. The method, which can detect sixteen benzodiazepines simultaneously, is highly sensitive and adequately specific. It is reliable for the analysis of these compounds in biological samples at therapeutic concentrations.     

Incomplete basis set problem. IV. Perturbative corrections to pair energies

A partitioning of the molecular Hamiltonian into the occupied and virtual orbital spaces and their orthogonal complement is introduced and used to develop a perturbation expansion of the exact ground-state energy relative to the Hartree–Fock energy computed using an incomplete basis set. The leading perturbation corrections to pair energies due to using the incomplete basis set are considered in detail. Summations of certain classes of pair contributions are discussed and a resummed correction is obtained.