New approach to oligotriazoles using a cobalt complex of propargyl azides as a synthetic component

We have developed an efficient method for preparation of triazolamers using a dicobalt hexacarbonyl complex of propargyl azides (CPA) as a synthetic component. Several types of CPAs possessing the side chains found in the natural amino acids were prepared by Nicholas reaction as well as by a reaction of propargyl azides with dicobalt octacarbonyl. Triazolamers with both amino and carboxyl termini were readily synthesized by repetitive reaction sequence involving a copper-catalyzed 1,3-dipolar cycloaddition followed by an oxidative deprotection.     

Determination of haptoglobin in human serum by high-performance gel-permeation chromatography

Summary A high-performance gel-permeation chromatographic (GPC) method is described for the determination of serum haptoglobin (Hp), based on the estimation of the haptoglobin-hemoglobin (Hp−Hb) complex. Hemoglobin (Hb) is added to the serum and the resulting Hp−Hb complex is separated by GPC and detected at 415 nm. The Hp−Hb complex separated chromatographically from serum migrated electrophoretically with the globulin fraction. It was found to be stable over a period of one week at 4°C. The total analysis time for a serum sample is approximately 20 min. The minimum detection limit is 30mg/L. Relative standard deviation values were below 1% (peak area). No interferences from bilirubin or from turbidity of samples were observed. The results of the GPC analysis correlate well with those obtained by nephelometric assay (r=0.996).     

Synthesis of polyester dendrimers and dendrons starting from Michael reaction of acrylates with 3-hydroxyacetophenone

A new AB₂ type building block for synthesis of dendritic compounds is made starting from Michael addition of 2 equiv of 3-hydroxyacetophenone to acrylate, followed by decarboxylation and deprotection of either carboxyl or hydroxyl protecting groups. [G1]-[G4] dendrons and [G2] dendrimer were synthesized by the reiterative [hydrogenolysis then DCC/DPTS coupling] sequence using a combination of convergent and divergent growth methods.     

Reaction of alkynyltrimethylsilanes with a hypervalent organoiodine compound: A new general synthesis of alkynyliodonium salts

New general methods for the synthesis of alkynyl(phenyl)iodonium tetrafluoroborate 2 from alkynyltrimethylsilanes 1 utilizing the combination of iodosylbenzene and triethyloxonium tetrafluoroborate or boron trifluoride etherate were developed. The medium effect observed in the reaction was also discussed.     

18O-tracer study on the rearrangement of carbonyl oxide intermediates to esters

A tracer study for the rearrangement of carbonyl oxides to esters using doubly-labeled oxygen lead to a conclusion that carbonyl oxides do not isomerize directly to dioxyranes and the rearrangement to esters proceeds via a cyclic tetroxide.     

Ultrasonic study on the elastic moduli of the NaTl (B32) structure

The elastic moduli and Debye temperatures of LiAl, LiIn, LiZn, NaIn and NaTl (NaTl type: space group Fd3m) have been determined at room temperature by an ultrasonic pulse transmission technique. The trend between the isotropic bulk modulus (B) and the volume per atom pair ($\text{M}\text{ρ}$) shows that the simple coulombic form of ion-ion interaction is not applicable to the NaTl type structure, while the semiconductor like diamond- or ZnS-, and ionic CsCl-type crystals have contributions from a coulombic attractive force. The bonding character of the NaTl structure is also discussed.