In-capillary preconcentration of proteins for capillary electrophoresis using a cellulose acetate-coated porous joint

This work describes the in-capillary preconcentration of proteins using a cellulose acetate-coated porous joint. The capillary wall near the inlet end of a capillary was made porous by HF etching. During the etching process, a voltage was applied across the capillary wall and the electric current across it was monitored. As the current passed through the capillary wall, it became porous. A solution of cellulose acetate in acetone was added to the etched porous joint. After the acetone was evaporated off, a cellulose acetate-coated porous joint was formed. To preconcentrate the protein ions, an electric voltage was applied between the inlet end of the capillary and the coated porous joint; the protein ions electromigrated to the porous joint but could not pass through it, while the buffer ions could pass easily through the joint. After allowing a certain amount of time for protein preconcentration, a separation voltage was applied across the two ends of the capillary, and normal capillary electrophoresis was carried out. The preconcentration factors for cytochrome c, lysozyme, ribonuclease, and chymotrypsinogen were 65, 155, 705, and 800, respectively. The cellulose acetate-coated porous joint was shown to be strong and stable over time, and was used to analyze trace proteins and macromolecules in biological samples.     

Highly stereoselective synthesis of functionalized beta,beta-di- and trisubstituted vinylic sulfoxides by Cu-catalyzed conjugate addition of organozinc reagents

beta,beta-Disubstituted chiral vinylic sulfoxides bearing functionalities have been synthesized via Cu-catalyzed conjugate addition of organozinc reagents to chiral 1-alkynyl sulfoxides. Due to the availability of functionalized organozinc reagents and high syn-selectivity of the reaction, both geometric beta,beta-disubstituted vinylic sulfoxides were selectively synthesized. Furthermore, 1-alkynyl sulfoxides were derivatized into trisubstituted vinylic sulfoxides by trapping the resulting alpha-sulfinyl vinylic carbanion with electrophiles. Highly diastereoselective THF and THP ring formations were accomplished by means of this methodology followed by an intramolecular Michael addition.     

Nuclear Wavepacket Study on Unimolecular Reactions of Hydrogen Cyanide Excited by Femtosecond Pulsed Lasers

The unimolecular reaction dynamics of hydrogen cyanide (HCN) induced by IR multiphoton, femtosecond excitations was studied on the basis of the nuclear wavepacket theory. Both hydrogen dissociation and migration of HCN are taken into account. In evaluating the propagation of the wavepackets in the two-dimensional potential surface, position grid and eigenfunction basis sets were adopted for the dissociation and hydrogen migration coordinates, respectively. The ground state potential energy function and the dipole moment function calculated by using a MCSCF ab-initio procedure were used. Laser-intensity dependencies of the dissociation and hydrogen migration probabilities were evaluated. Effects of mode-couplings on the hydrogen migration were examined.     

Newton's formula for

This paper presents an explicit relation between the two sets which are well-known generators of the center of the universal enveloping algebra of the Lie algebra : one by Capelli (1890) and the other by Gelfand (1950). Our formula is motivated to give an exact analogy for the classical Newton's formula connecting the elementary symmetric functions and the power sum symmetric functions. The formula itself can be deduced from a more general result on Yangians obtained by Nazarov. Our proof is elementary and has an advantage in its direct accessibility.

     

Stereodivergent and reiterative synthesis of bistetrahydrofuran ring cores of annonaceous acetogenins

Eight diastereoisomers of the bistetrahydrofuran ring cores of annonaceous acetogenins have been synthesized by asymmetric alkynylation of alpha-tetrahydrofuranic aldehydes and stereodivergent one-pot tetrahydrofuran (THF) ring formation. In all cases, the asymmetric alkynylation proceeded with very high diastereoselectivity to give eight kinds of optically pure THF cores. We also describe a comparison of the (1)H and (13)C NMR spectral data of the eight isomers and give full details of the THF ring construction.     

Pd-catalyzed sulfinylzincation of activated alkynes with 1-alkynyl sulfoxides as a sulfinyl source

Unprecedented Pd-catalyzed sulfinylzincation with 1-alkynyl sulfoxide as a sulfinyl source was developed. Bis-sulfinyl alkenes were formed in good yields on treatment of 1-alkynyl sulfoxides with Et(2)Zn in the presence of a Pd-catalyst, wherein zinc sulfenate (or sulfinylzinc) species would be generated in situ to undergo highly syn-selective conjugate addition to the 1-alkynyl sulfoxides. By using 3,3-dimethyl-1-butynyl sulfoxides, formation of the bis-sulfinyl alkenes was completely suppressed and the sulfinylzincation of activated alkynes was accomplished. The reaction tolerates various functionalities, and was promoted considerably by the neighboring group participation of the heteroatom at the delta-position in the alkynoates. Stereodivergent synthesis of two diastereomeric vinylic sulfoxides and reaction of the resulting vinylzinc species with electrophiles were also described.     

Diastereoselective Ni(0)-catalyzed carbocyclization to chiral vinylic sulfoxide

Diastereoselective Ni(0)-catalyzed carbocyclization of enone to chiral vinylic sulfoxide has been accomplished, wherein two stereogenic centers were constructed simultaneously to give cis- and trans-disubstituted cyclopentanes from (E)- and (Z)-vinylic sulfoxides, respectively.     

Systematic synthesis of Bis-THF ring cores in annonaceous acetogenins

Systematic synthesis of bis-THF ring cores, synthetic intermediates of adjacent bis-THF annonaceous acetogenins, has been achieved by asymmetric alkynylation and subsequent stereodivergent THF ring formation. The asymmetric alkynylation of alpha-tetrahydrofuranic aldehyde with (S)-3-butyne-1,2-diol derivatives gave good yields of erythro- and threo-adducts with very high diastereoselectivity. These adducts were converted into four types of bis-THF cores via two kinds of one-pot THF ring formation. [reaction: see text]     

Geometrically selective synthesis of functionalized beta,beta-disubstituted vinylic sulfoxides by Cu-catalyzed conjugate addition of organozinc reagents to 1-alkynyl sulfoxides

[reaction: see text] A new synthetic method of chiral beta,beta-disubstituted vinylic sulfoxides bearing various functionalities has been developed by employing Cu-catalyzed conjugate addition of an organozinc reagent to chiral 1-alkynyl sulfoxide. Since the reaction proceeds with very high syn-selectivity, both geometric beta,beta-disubstituted vinylic sulfoxides were stereoselectively synthesized by changing the combination of 1-alkynyl sulfoxide and the organozinc reagent.