Functional monomers and polymers. CII. Synthesis and properties of oligomer models of polyethyleneimine derivatives containing pendant adenine bases

A series of oligomer model compounds of polyethyleneimine derivatives with pendant adenine bases were prepared by the reaction of a carboxyethyl derivative of adenine with oligomeric amines, using an activated ester method. To evaluate the intramolecular interaction between pendant adenine bases in these compounds, ultraviolet spectra at various pH regions were measured. Ultraviolet hypochromicities and pK_a values depended linearly on the chain length of the oligomers. The results showed that the intramolecular interactions of adenine bases were realized less in their protonated than neutral forms.     

Total synthesis of 12-methoxydihydrochelerythrine and anti-tumour activity of its quaternary base: toward an efficient synthetic route for 12-alkoxybenzo[c]phenanthridine bases via naphthoquinone monooxime from 2-benzofuranyl-1-tetralone derivative

A concise total synthesis of 12-methoxydihydrochelerythrine (6), isolated from Bocconia integrifolia, is described. The synthesis features an efficient route to a 12-alkoxybenzo[c]phenanthridine skeleton via naphthoquinone monooxime 11 as a key compound. Starting from 7-methoxy-2-methylbenzo[b]furan (9), 3-aryl-1-tetralone 10 was synthesised, followed by aromatisation to 3-aryl-1-naphthol 17. After oxidative cleavage of the furan ring, basic nitrosation of naphthol 22 gave the naphthoquinone 11. The benzo[c]phenanthridine skeleton was formed by reductive cyclisation of 11. Deoxygenation of the lactam moiety in 23 afforded nor-base 32 and methylation of 32 under reductive conditions gave the target dihydro base 6 (23 steps from benzofuran 9 in 10% overall yield). The corresponding quaternary base 7 showed moderate anti-tumour activity against cancer cell lines; on NCI-H460: IC50 4.5 microM and on MDA-MB-231: IC50 1.2 microM. Introduction of a methoxy group into the 12-position of the benzo[c]phenanthridine skeleton could cause enhanced activity against MDA-MB-231 by comparison of 7 with chelerythrine (35) (IC50 5.3 microM).     

Stannylative cycloaddition of enynes catalyzed by palladium-iminophosphine

Palladium-iminophosphine complex catalyzes stannylative cycloaddition of conjugated enynes using hexabutyldistannoxane as a stannylating agent to afford highly substituted 3-alkenylphenylstannanes regioselectively. Stannylative cross-cycloaddition reactions between different enynes or between enynes and diynes are also achieved. The reaction is successfully applied to a concise synthesis of alcyopterosin N, which has been isolated recently from sub-Antarctic soft coral, Alcyonium paessleri.     

Dielectrophoretic micropatterning with microparticle monolayers covalently linked to glass surfaces

Two-dimensional micropatterns of microparticles were fabricated on glass substrates with negative dielectrophoretic force, and the patterned microparticles were covalently bound on the substrate via cross-linking agents. The line and grid patterns of microparticles were prepared using the repulsive force of negative dielectrophoresis (n-DEP). The template interdigitated microband array (IDA) electrodes (width and gap 50 mum) were incorporated into the dielectrophoretic patterning cell with a fluidic channel. The microstructures on the glass substrates with amino or sulfhydryl groups were immobilized with the cross-linking agents disuccinimidyl suberate (DSS) and m-maleimidobenzoyl-N-hydroxy-succinimide ester (MBS). Diaphorase (Dp), a flavoenzyme, was selectively attached on the patterned microparticles using the maleimide groups of MBS. The enzyme activity on the patterned particles was electrochemically characterized with a scanning electrochemical microscope (SECM) in the presence of NADH and ferrocenylmethanol as a redox mediator. The SECM images proved that Dp was selectively immobilized onto the surface of microparticles to maintain its catalytic activity.     

'Thiacalix[4]aniline' as a highly specific extractant for Au(III) and Pd(II) ions

Thiacalix[4]aniline (4), a cyclic tetramer of p-tert-butylaniline bridged with four sulfides, extracted Au(III) and Pd(II) ions specifically from acidic solutions among 41 metal ions including soft metal ions such as Hg(II), Cd(II), Zn(II), Pb(II), and Cu(II).     

Inhibitory activities of novel pyrimidine derivatives on the contact hypersensitivity reaction

In order to obtain novel topically applied anti-inflammatory compounds containing an inexpensive anti-oxidative moiety without chirality, we synthesized compound 2c derivatives having a di-tert-butylphenol moiety, and evaluated by topical administration their anti-inflammatory potentials on picryl chloride-(PC) induced contact hypersensitivity reaction (CHR) in mice. In the course of our structure-activity relationship (SAR) studies on the pyrimidine or the anti-oxidative moiety and the linker between them, the most potent compounds (10, 11) were obtained by the insertion of a C2 unit in compound 2c. The potencies of these compounds were 2-fold greater than that of 1. Compounds 10 and 11 were considered to be useful lead compounds having inexpensive anti-oxidative moieties without chirality.     

Reaction and characterization of thioamide dianions derived from N-benzyl thioamides

Thioamide dianions were generated by the highly efficient reaction of N-benzyl thioamides with 2 equiv of BuLi. Alkylation, allylation, and silylation took place selectively at the carbon atom adjacent to the nitrogen atom of the thioamide dianions. Oxiranes and an aldehyde were also used as electrophiles in the reaction of thioamide dianions to form N-thioacyl 1,3- or 1,2-amino alcohols. The insertion reaction of elemental sulfur to a thioamide dianion and subsequent ethylation afforded a N-thioacyl hemithioaminal. NMR studies on the thioamide mono- and dianions derived from N-benzyl 2-methoxythiobenzamide showed a linear relationship between the chemical shifts of all carbon atoms of thioamide mono- and dianions. The results also suggested that the negative charge at the benzylic carbon atom of the dianion is not fully delocalized. The charge distribution patterns of the dianion are consistent with those of pi polarization.     

A Lower Bound for the Sectional Genus of Quasi-Polarized Surfaces

Let (X,L) be a quasi-polarized variety, i.e. X is a smooth projective variety over the complex numbers and L is a nef and big divisor on X. Then we conjecture that g(L) = q(X), whereg(L) is the sectional genus of L and . In this paper, we treat the case . First we prove that this conjecture is true for , and we classify (X,L) withg(L)=q(X), where is the Kodaira dimension of X. Next we study some special cases of .     

Metal-Assisted Crown Ethers for Evolutionary Design of Metal Hosts

The idea of metal-organization of linear molecules into macrocyclic structures is introduced. This idea has been tested on various oligoether compounds containing two chelate ligands at the terminals. Chelate ligands include -diketone, salicylic ester, catechol, and salicylic acid. The first two were organized into neutral metallocrown ethers, which showed much better extraction behavior towards alkali and alkaline earth metal cations than conventional monocyclic crown ethers. The last two were organized into ate-type complexes and incorporated metal ions into a newly formed anionic cavity. The stability constants were estimated for salicylate complexes and revealed excellent binding and selectivity. The presence of dipolar O--–Mn+ bonds in the metal organization method is concluded to contribute significantly to better interaction with metal ions through enthalpic stabilization.