On global solvability of non-linear viscoelastic equations in the analytic category

We prove the global existence of analytic solutions to the non-linear viscoelastic equations of the following type: where ? and ψ are continuous and non-negative functions satisfying some additional conditions. The method of the analytic energy estimates is used.     

Syntheses of chiral homoazacalix[4]arenes incorporating amino acid residues: molecular recognition for racemic quaternary ammonium ions

Chiral calixarene analogues incorporating amino acid residues into the macrocyclic rings were prepared from the cyclization reactions of bis(chloromethyl)phenol-formaldehyde tetramer with amino acid methyl ester in moderate yields. The macrocycles form a chiral concavity, which is induced by the chiral transmission from the point chirality of the amino acid residues to the phenol-formaldehyde tetramer unit. The macrocycles have the cavity pi-basic enough to include the quaternary ammonium ion due to the cation-pi interaction and can serve as a shift reagent for racemic ammonium ions during 1H NMR analysis.     

Automatic log P estimation based on combined additive modeling methods

Summary A program for the automatic estimation of the logarithm of the partition coefficient between 1-octanol and water phases (log P) has been developed as a component of a system entitled CHEMICALC (Combined Handling of Estimation Methods Intended for Completely Automated Log P Calculation). Log P values are calculated based on additive group contributions to log P. Three sets of groups are defined, and their contributions have been derived from the experimental log P values of 1465 molecules. The system divides a structural formula of a compound of interest into the groups whose increments are provided and then calculates its log P value. All processing after structure input is fully automated. This system has been tested for predicting the log P values of 1686 compounds. The accuracy is sufficient for many practical purposes.     

Pressure control of enantiodifferentiating polar addition of 1,1-diphenylpropene sensitized by chiral naphthalenecarboxylates

Effects of pressure on the enantiodifferentiating methanol addition to 1,1-diphenylpropene (1) sensitized by chiral naphthalenedicarboxylates (3 and 4) were investigated over 0.1-400 MPa. The logarithm of enantiomeric excess (ee) of photoadduct, i.e. 1,1-diphenyl-2-methoxypropane (2), was a linear function of both pressure (P) and temperature (T); further, the product chirality was switched by P in some cases. From the slope of P- ln(k(R)/k(S)) plot, the differential activation volume (Delta DeltaV(double dagger)) was determined for the first time for bimolecular asymmetric photoreactions. The Delta DeltaV(double dagger) values obtained are mostly larger than those obtained for relevant unimolecular photoreactions, and are a critical function of the nature of the chiral auxiliary and solvent, indicating conformation changes of the intervening diastereomeric exciplex or transition state in different solvents. Indeed, fluorescence spectral examinations of the sensitizer and exciplex under high pressure revealed the existence of exciplexes of variable energy and structure, which may rationalize the different Delta DeltaV(double dagger) and product ee obtained. A three-dimensional diagram, correlating the ee with P and T, was constructed from the pressure dependence data at different T, from which we may propose an idea of the multidimensional control of asymmetric reaction by the combined use of the entropy-related environmental factors.     

Preparation and antitumor activity of 2'-O-, 3'-O- and 2',3'-di-O-substituted derivatives of etoposide.

The 2'-O-, 3'-O- and 2',3'-di-O-substituted derivatives (4a--p) of etoposide were prepared by nucleophilic substitution of 4'-O-benzyloxycarbonyletoposide (2) followed by deprotection. Controlled reaction (a limited amount of reagents and low temperature) was required for preparing the mono-O-substituted derivatives. In terms of ED125 values, doses which show 125% of T/C against P388 leukemia in mice, both the 2'-O-acetate (4a, ED125 = 0.18 mg/kg) and 3'-O-acetate (4b, 0.23 mg/kg) were nearly as active as etoposide (1, 0.19 mg/kg), while the 2',3'-di-O-acetate (4c, 1.9 mg/kg) was somewhat less potent. In the replacement with other substituents, antitumor activity of the 2'-O-substituted derivatives was affected much more by the difference of the substituents as compared with that of the corresponding 3'-O-substituted derivatives. In the 2',3'-di-O-substituted derivatives, the activity was decreased additively on the substituents.     

Spectroscopy of Ar-SH and Ar-SD. II. Determination of the three-dimensional intermolecular potential-energy surface

All the pure rotational transitions reported in the previous studies [J. Chem. Phys. 113, 10121 (2000); J. Mol. Spectrosc. 222, 22 (2003)] and newly observed rotation-vibration transitions, P = 1/2 <-- 3/2, for Ar-SH and Ar-SD [J. Chem. Phys. (2005), the preceding paper] have been simultaneously analyzed to determine a new intermolecular potential-energy surface of Ar-SH in the ground state. A Schrodinger equation considering the three-dimensional freedom of motion for an atom-diatom complex in the Jacobi coordinate, R, theta, and r, was numerically solved to obtain energies of the rovibrational levels using the discrete variable representation method. A three-dimensional potential-energy surface is determined by a least-squares fitting with initial values of the parameters for the potential obtained by ab initio calculations at the RCCSD(T)/aug-cc-pVTZ level of theory. The potential well reproduces all the observed data in the microwave and millimeter wave regions with parity doublings and hyperfine splittings. Several low-lying rovibrational energies are calculated using the new potential-energy surface. The dependence of the interaction energy between Ar and SH(2pi(i)) on the bond length of the SH monomer is discussed.     

Total synthesis and the absolute configuration of citreoviral and citreoviridin

Both citreoviral and citreoviridin, metabolites of $\text{Penicillium citreo-viride}$ B., have been synthesized starting from D-glucose, in connection with which their absolute configuration has also been established.     

A new method for partition of interaction energy. Relation between stabilization energy and orbital mixing

A new method for partition of interaction energy is proposed. The scheme given here easily connects the calculated stabilization energy with the orbital mixing in analyzing orbital interactions of molecules. The method can reveal the relation between the change of electron distribution and stabilization energy. As an example, orbital interaction energies are estimated for diazocompounds, diazomethane and diazirine.     

The first chemical conversion of l-proline to l-glutamic acid

The ruthenium tetroxide oxidation of N-acyl-l-proline esters gave the corresponding l-pyroglutamic acid derivatives in good yields with no appreciable racemization, which led to the first chemical conversion of l-proline to l-glutamic acid.     

Quantum chemical study on the configurations of encapsulated metal ions and the molecular vibration modes in endohedral dimetallofullerene La2@C80

The configuration of La ions of La(2)@C(80) in the [80]fullerene cage was investigated by use of quantum chemical calculations. We found that the D(3)(d)() configuration is the global minimum in total energy, being more stable by 1.9 kcal/mol than the D(2)(h)() configuration, which has been considered to be the most stable. The potential energy surface calculation clarified that La ions travel between 10 equivalent D(3)(d)() positions through D(2)(h)() positions and consequently form pentagonal dodecahedral trajectory, which is in good agreement with the previous synchrotron radiation structural study. The experimental and theoretical investigation of the Raman spectrum revealed that the symmetry of molecular vibration is dramatically reduced simply by encapsulation of two La ions, and resulting vibrational modes were successfully assigned. The Raman peak at 163 cm(-)(1) was interpreted as the in-phase synchronously coupled mode of the [80]fullerene cage elongation and the La-La stretching, rather than a conventional and naive assignment as a metal-to-cage vibration mode.