The synthesis of isoquinoline alkaloid and its related compounds using alanine derivatives as chiral auxiliaries

Chiral 1-substituted isoquinoline derivatives, which were obtained by the reaction using alanine derivatives as chiral auxiliaries, were transformed to (S)-2,3,9,10,11-pentamethoxyhomoprotoberberine (7) and a synthetic intermediate for O-methylkreysigine (9) in good yields and high stereoselectivity. The corresponding chiral allyl derivative of isoquinoline was transformed to a pyrrolidinoisoquinoline (16) in a highly enantioselective manner.     

Effect of monomer concentration on characteristics of methacrylic acid-grafted polyethylene film prepared by photografting

The effect of monomer concentration on photografting of methacrylic acid (MAA) onto linear low-density polyethylene (PE) film (thickness=30 μm) was investigated at 60 °C in water solvent together with the location of MAA-grafted chains. Xanthone was used as a photoinitiator which was coated on the film sample earlier. The higher percentage of grafting and graft efficiency were afforded for the system with the higher monomer concentration. The resultant MAA-grafted films were subjected to measurements of pH-responsive character and ability to adsorb cupric ion in order to understand the characteristics of function introduced. The grafted samples exhibited the pH-responsive character, where they shrank and swelled in acidic and alkaline media, respectively. The pH-responsive character of the grafted films was higher for the samples prepared in the system with a higher monomer concentration. Moreover, the grafted samples exhibited the ability to adsorb cupric ion, and the ability was reduced when the sample was prepared in the system with a higher monomer concentration. The different extents of the pH-responsive character and ability to adsorb cupric ion of the resulting grafted PE films were discussed in terms of location of grafted chains in the film substrate, which was determined by a scanning electron microscope and an attenuated total reflection infrared spectroscopy.     

Studies on palytoxins

The complete structure of palytoxin (1) was elucidated by us in 1982.¹ Our continuous interests in palytoxin led us to examine minor constituents of Okinawan Palythoa tuberculosa. In this paper, we describe successful isolation and structural elucidation of four minor toxins, which were named homopalytoxin (2), bishomopalytoxin (3), neopalytoxin (4) and deoxypalytoxin (5).     

Reactions of metal tert-butoxides with aromatic sulfonyl chlorides. A new synthesis of di-tert-butyl ether

Di-tert-butyl ether was synthesized in good yields by the S_N reactions of lithium tert-butoxide with tosyl and p-bromobenzenesulfonyl chlorides under mild conditions.     

A new route to methyl (R,E)-(-)-tetradeca-2,4,5-trienoate (pheromone of Acanthoscelides obtectus) utilizing a palladium-catalyzed asymmetric allene formation reaction

[reaction: see text] A formal total synthesis of the sex attractant of male dried bean beetle, methyl (R,E)-(-)-tetradeca-2,4,5-trienoate, was achieved by a new efficient route utilizing the Pd-catalyzed asymmetric allene synthesis reaction. It was found that the atropisomeric biaryl bisphosphine (R)-segphos showed better enantioselectivity than (R)-binap in the Pd-catalyzed reaction for preparing alkyl-substituted axially chiral allenes.     

Addition reactions of pendant epoxide group in poly(glycidyl methacrylate) with various active esters

Addition reactions of pendant epoxide groups in poly(glycidyl methacrylate) (PGMA) with various active esters such as 1-benzotriazolyl benzoate, S-(2-benzoxazolyl) thiobenzoate, S-(2-benzothiazolyl) thiobenzoate, 4-nitrophenyl benzoate (4NPB), and S-phenyl thiobenzoate (PTB) were carried out using quaternary salts as catalysts. The reactions of PGMA with those active esters proceeded in diglyme at 100°C for 24 h quantitatively without the formation of 2-hydroxyl pendant groups in the polymer when 10 mol % of tetraethylammonium bromide was used as a catalyst. Furthermore, it was found that the respective quaternary salts have higher catalytic activity than tertiary amines in the reaction of PGMA with the active esters, and the reaction of PGMA with 4NPB gave the corresponding polymer with the highest conversion by addition of tetrabutylammonium bromide as a catalyst, while tetraethylammonium chloride showed the highest activity for the reaction of PGMA with PTB. In addition, the rate of reaction of PGMA with 4NPB was proportional to third order kinetics of the epoxide concentration, the ester concentration and the catalyst concentration as follows: ?d[Epoxide]/dt = ?[Ester]/dt = k₃[Epoxide] [Ester] [Catalyst].     

Efficient photochemical oxetane formation from 1-methyl-2,4,5-triphenylimidazole and benzophenones

In contrast to simple imidazoles, 1-methy1–2,4,5-triphenylimidazole ($\text{1}$) produced stable oxetane photoadducts $\text{3b}$ - $\text{e}$ with good efficiency upon irradiation in the presence of benzophenone derivatives $\text{2b}$ - $\text{e}$ in acetonitrile solution. Irradiation in the solid-phase was also studied. The oxetanes $\text{3b}$ - $\text{e}$ readily underwent cycloreversion by acid catalysis or by heating.     

Polymerization of methacrylates. I. Polymerization reactivity of picryl methacrylate

The polymerization of picryl (PMA), 2,4-dinitrophenyl (2,4-DNMA),2,6-dinitrophenyl (2,6-DNMA), 2-methyl-4,6-dinitrophenyl (MDNMA), and 2,6-dimethylphenyl methacrylates (DMMA) was carried out in benzene at 60°C. PMA, 2,6-DNMA, and MDNMA did not undergo radical homopolymerization, while 2,4-DNMA and DMMA did. The results suggest that the growing radical readily attacks the oxygen atom of the nitro group at the 2 position of the terminal phenyl group due to the steric effect of the substituent at the 6 position, resulting in chain termination. PMA formed a charge-transfer complex with 2-naphthyl methacrylate (NMA). The stoichiometric composition of this complex was shown to be 1:1 molar complex. PMA was readily copolymerized with NMA. The amount of solvent affected the composition of the copolymer obtained at a given same mole fraction in feed. The results suggest that charge-transfer interaction between the ester groups affects the copolymerization mechanism.     

Wang resin-type linker containing a nitro group for polymer support oligosaccharide synthesis: polymer-supported glycosyl donor

A nitro-introduced Wang resin-type linker for soluble and insoluble polymer support oligosaccharide synthesis is described. The linker was used for connecting glycosyl donors and polymer supports, and was completely stable under the glycosylation conditions tested. The cleavage of the linker was performed under reductive conditions without affecting the protecting groups to release disaccharides.     

Prompt gamma-ray analysis using cold and thermal guided neutron beams

The extraction behavior of uranium(VI), plutonium(IV) and some fission products like zirconium(IV), ruthenium(III) and europium(III) from 3.5M nitric acid with -irradiated organic phase pre-equilibratedn-dodecane solutions of dihexyl derivatives of hexanamide (DHHA), octanamide (DHOA) and decanamide (DHDA) has been investigated as a function of absorbed dose upto 184·10⁴ Gy. The results indicate that the extraction of uranium(VI) decreases gradually with dose upto 72·10⁴ Gy and becomes almost constant thereafter, while, the extraction of plutonium(IV) decreases upto a dose of 20·10⁴ Gy and then increases rapidly up to a dose of 82·10⁴ Gy indicating synergistic effects of radiolytic products formed at higher doses. Extraction of zirconium(IV) increases gradually upto a dose of 72·10⁴ Gy. Europium(III) does not get extracted with any of these amides in the entire dose range (0–184·10⁴ Gy) studied, however, ruthenium shows insignificant increase in extraction with dose. The decrease inD values noticed in the case of plutonium and zirconium after the dose of 72·10⁴ Gy which was attributed to the third phase formation and emulsification. Infrared studies confirm the final products of radiolysis as the respective amines and carboxylic acids. The degraded amide contents have been estimated by quantitative IR spectrophotometric technique. Extraction data obtained for uranium(VI) and plutonium(IV) with TBP/n-dodecane system have also been compared under similar experimental conditions.