Short-step synthesis of optically and biologically active exo-brevicomin

Optically and biologically active (IR,5S,7R)-(+)-exo-brevicomin was synthesized in the six-step sequence starting from diethyl (S,S)-(−)-tartrate.     

Imino ene reaction catalyzed by ytterbium(III) triflate and TMSCl or TMSOTf

A novel combined system of Yb(OTf)(3) with TMSCl or TMSOTf catalyzed an imino ene reaction. The reaction of N-tosylbenzaldimine (1) with alpha-methylstyrene (2) proceeded smoothly to give homoallylic amine 3 in the presence of a catalytic amount of Yb(OTf)(3) and TMSCl. This catalytic system was successfully applied to the imino ene reactions of various aldimines with alkenes. This new imino ene reaction provides a unique method for the three-component coupling reaction of an aldehyde, tosylamide, and alpha-methylstyrene in the presence of Yb(OTf)(3) and TMSOTf, to give the corresponding homoallylic amine.     

Syntheses of (5E)-PGE2 and New 6-Functionalized Derivatives by the Use of Palladium-Catalyzed Decarboxylative Allylic Alkylation

(5 )-Prostaglandin E₂ (7) was synthesized fron ( )-4- -butyldimethylsilyloxy-2-cyclopentenone (1) by 2-alkenyloxycarbonylatlon of the organocopper conjugate-addition adduct (3) followed by intramolecular palladium-catalyzed decarboxylative allylic alkylation. The (5 )-prostaglandin E₂ skeleton was also obtained from the β-keto allylic ester (11) by a similar decarboxylative allylic alkylation. The decarboxylative allylic alkylation of another type of the three-component coupling product (12) gave new 6-methyleneprostaglandin E1 skeleton (15a), which was converted into new 6-methylprosta-glandin I methyl ester (20) 6-methyleneprostaglandin F₁ derivative (16) by two different ways. The stereochemistry of this intramolecular decarboxylative allylic alkylation was discussed in the reaction of 2-[( )- or ( )-2-butenyloxy-carbonyl] cyclopentanone systems.     

Eisenpentacarbonyl-induzierte Reaktionen von Norbornadien und substituierten Olefinen

Iron Pentacarbonyl Induced Reactions of Norbornadiene and Substituted Olefins The photochemical reaction of norbornadiene and α, β-unsaturated nitriles, esters and amides in the presence of Fe(CO)₅ was studied. Nitriles furnished the dinorbornenyl ketones 2a-c (Scheme 1). Esters led to an addition of a norbornene moiety to the double bond giving the substituted α, β-unsaturated esters 10a and 10b (Scheme 5). Methacrylamide and methyl β-aminocrotonate gave the cyclopentanone derivatives 14 and 17 , respectively (Schemes 7 and 8). The reaction was in all cases highly stereoselective with general exo-substitution on the norbornadiene. The attack on the unsymmetric olefins occurred regiospecifically at that point of the double bond which was furthest away from the functional group. A plausible mechanism for these reactions is suggested in Schemes 10 and 11 .     

Fluorimetric enzyme immunoassay for serum β2-microglobulin based on the horseradish peroxidase-labeled Fab′ fragment of immunoglobulin

A sensitive sandwich-type enzyme immunoassay for human β₂-microglobulin in serum is described. Rabbit anti-human β₂-microglobulin IgG is coated on a styrene-maleic anhydride copolymer bead, which is incubated with β₂-microglobulin in serum sample at 30°C for 1 h, and again incubated at 30°C for 1 h with a conjugate of anti-β₂-microglobulin Fab′ (a fragment of rabbit anti-human β₂-microglobulin IgC) and horseradish peroxidase to form a sandwich-type immunocomplex. The conjugate is prepared with a heterobifunctional reagent, N-succinimidyl-3-(2-pyridyldithio)propionate. The peroxidase activity of the immunocomplex is measured spectrofluorimetrically by use of 3-(p-hydroxyphenyl)propionic acid. The method permits precise assay of 0.05–10 ng of β₂-microglobulin in serum, with calibration linearity up to 1.0 ng of protein.     

Studies on propagating species in cationic polymerization of styrene derivatives by acetyl perchlorate or iodine. II. Salt effect on the relative reactivity in the cationic copolymerization of styrene derivatives with 2-chloroethyl vinyl ether initiated by iodine

To determine the effect of the dissociation of propagating species on the relative reactivity of monomers, 2-chloroethyl vinyl ether was copolymerized with p-methoxystyrene or with p-methylstyrene by using iodine in various solvents at 0°C. A common-ion salt (tetra-n-butylammonium iodide or tetra-n-butylammonium triiodide) was added to these copolymerization systems in a polar solvent to depress the dissociation of the propagating species. The addition of a common-ion salt increased the vinyl ether content in the copolymer. The more the dissociation of propagating species was depressed, the more the vinyl ether content in the copolymer increased. This effect of common-ion salt was in agreement with that of decreasing solvent polarity which yielded vinyl ether-rich copolymer as well. Therefore, the change of the monomer reactivity ratio by the solvent polarity, which used to be explained in terms of a selective solvation, must be reconsidered from the viewpoint of varying degrees of the dissociation of propagating species.     

Amphiphilic copolymers with increased affinity for substrates

The copolymers of methyl quaternized 2-dimethylaminoethyl acrylate and styrene, 2-vinyl naphthalene, acrylic acid iso-octyl ester, or acrylic acid n-butyl ester have been prepared. Studies were made of the binding of a “binding probe,” methyl orange, by the copolymers in aqueous solution. The first binding constants and the thermodynamic parameters in the course of the binding were evaluated. Furthermore, the intensity of fluorescence of a hydrophobic fluorescent probe, 2-p-toluidinylnaphthalene-6-sulfonate, in the presence of these polymers was investigated. In addition, the fluorescence spectra of monomer and excimer emissions of the polymers with aromatic residues were measured. The excimer/monomer fluorescence intensity ratio was studied in the presence of various additives such as methyl orange, urea, methanol, and NaCl to gain an insight into the nature of microdomains in the polymer. The nature and phenomena of dye binding and hydrophobic fluorescent probe binding with the polymers are discussed. © 1993 John Wiley & Sons, Inc.     

Synthesis of both the enantiomers of sclerosporin and sclerosporal,sporogenic substance of sclerotinia fructicola1

Both the enantiomers of sclerosporin $\text{1}$ and sclerosporal $\text{2}$ were synthesized from (-)-carvone. (4R,9R,10S)-(+)-Sclerosporin and (4R,9R,10S)-(-)-sclerosporal were identified as the natural enantiomers by a comparison of their CD-spectra. An intramolecular Diels-Alder route was proved to be an efficient method of preparing sufficient amounts of (+)-$\text{1}$ for the biological study.     

Poly(diacetylene)-nanofibers can be fabricated through photo-irradiation using natural polysaccharide schizophyllan as a one-dimensional mold

Schizophyllan interacts with various 1,4-diphenylbutadiyne derivatives to induce their chirally-twisted packing. A series of referential experiments using other polysaccharides (amylose, pullulan, dextran, etc.) and a carbohydrate-appended detergent (dodecyl-beta-d-glucopyranoside) indicates that these 1,4-diphenylbutadiyne derivatives are accommodated within a tubular cavity constructed by a helical superstructure of schizophyllan. In these 1,4-diphenylbutadiyne derivatives, 1,4-bis(p-propionamidophenyl)butadiyne can be easily polymerized through UV-irradiation, in which schizophyllan acts as a one-dimensional mold to produce the corresponding poly(diacetylene)s with fibrous morphologies. Detailed investigations on this unique approach to prepare the nanofibers revealed that it includes two individual processes, that is, 1) UV-mediated polymerization of encapsulated 1,4-bis(p-propionamidophenyl)butadiyne to produce immature nanofibers and 2) their reorganization through hydrophobic interfiber interactions into ordered nanofibers. The other 1,4-diphenylbutadiyne derivatives could not be polymerized through UV-irradiation, indicating that the p-propionamido-functionalities play substantial roles for a suitable packing of the monomer for the polymerization. The other 1,4-diphenylbutadiyne derivatives, however, can be also polymerized through gamma-ray irradiation in the presence of schizophyllan to give the corresponding poly(diacetylene)-nanofibers, emphasizing the wide applicability of the schizophyllan-based strategy for polymerization of various 1,4-diphenylbutadiyne derivatives.     

Stable metallic behavior and antiferromagnetic ordering of Fe(III) d spins in (EDO-TTFVO)2.FeCl4

We report the crystal structure and physical properties of the 2:1 FeCl4- salt of a new donor molecule, EDO-TTFVO. Crystal structure analysis of this salt revealed that the donor molecules formed a beta' '-type two-dimensional conducting layer, and there is a short S...Cl contact between the donor molecules and the FeCl4- ions, which is expected to mediate a strong pi-d interaction. This salt showed a stable metallic conducting behavior down to 0.3 K and an antiferromagnetic ordering at TN approximately 3.0 K, indicating that this salt becomes a new antiferromagnetic molecular metal at ambient pressure. The appearance of the magnetic ordering is considered to originate from the strong pi-d interactions between the donor molecules and the FeCl4- ions because the field dependence of magnetoresistances was remarkably affected below the antiferromagnetic transition temperature.