Mamiko Okada

The aromatization of Hantzsch dihydropyridines with nitric oxide (NO)

Abstract Hantzsch dihydropyridines were readily oxidized by nitric oxide to give corresponding pyridines in quantitative yields. This reaction system required no work-up procedure. In the presence of oxygen, it was possible to reduce nitric oxide to less than an euimolar amount. This is the first reaction of nitric oxide itself that is practical for synthetic use.

Oxidation of 1-aminopyrazoles and synthesis of 1,2,3-triazines

Oxydation par Pb(OAc) 4 , PbO 2 /acide trifluoroacetique et/ou peroxyde de nickel/acide acetique

A NEW ENTRY TO THE ETHYNYLATION OF AZAAROMATICS USING BIS(TRIBUTYLSTANNYL)ACETYLENE IN THE PRESENCE OF ALKYL CHLOROFORMATE

Abstract Unstable N -alkoxycarbonyl quaternary salts of azaaromatics were trapped in situ by bis(tributylstannyl)acetylene followed by the treatment with trifluoroacetic acid to give 2-ethynyl adducts in good yields. The same compounds were obtained only in low yields when ethynyltributyltin was used as a nucleophile. The reaction was revealed to be available for various aromatics including pyridine, pyridazine, imidazole, thiazole, oxazole, and benzodiazines.

The substitution of 5-halo-1,2,3-triazines with electrolytically generated superoxide

Abstract Electrolytically generated superoxide reacted with 5-halo-1,2,3-triazines 1 to afford 5-hydroxy-1,2,3-triazines 2. Reaction of 1 with hydroxide anion or potassium superoxide resulted in complicated mixture of products, therefore the reaction was specific for electrogenerated superoxide. The reaction mechanism was investigated with electrochemical methods, and it was revealed that one electron transfer from superoxide to 1 initialized the reaction.

The reactivity of monocyclic 1,2,3-triazine

The reactivity of unsubstituted 1,2,3-triazine was investigated using various nucleophilic and electrophilic reagents, molecular orbital calculations, and low temperature nmr measurements

Radical nucleophilic carbamoylation of 1,2,3-triazine derivatives

Radical nucleophilic carbamoylation was carried out to various 1,2,3-triazine derivatives. In the case of parent triazines as substrates, Miniscis system was not effective, and in the absence of acid, a small amount of radical adduct was obtained. Triazinium dicyanomethylides reacted with carbamoyl radical to give 5-carbamoyltriazines in good yields. Other 1,2,3-triazine derivatives were also investigated

Reaction of imidazoles with allyltributyltin in the presence of chloroformate

Abstract The reaction of imidazoles with allyltributyltin in the presence of chloroformate gave 2-allyl-1,3-dialkoxycarbonyl-4-imidazolines in good yields. The addition products were aromatized with potassium ferricyanide under basic condition to afford corresponding 2-allylimidazoles.

The reaction of 3,3′-dimethyl-2,2′-bithiazolinium salts with superoxide

Abstract The reaction of 3,3′-dimethy]-2,2′-bithiazolium salts with potassium superoxide afforded new ten-membered ring compounds 1,2,5,8-dithiadiazecin-6,7-diones in moderate yields. Since these compounds were not obtained from the reaction of KOH-O2 or KOH-H2O2, the reaction is revealed to be specific for superoxide.

Radical carbamoylation of 1,2,3-triazinium 2-dicyanomethylides

The nucleophilic radical carbamoylation of 4,6-disubstituted 1,2,3-triazinium 2-dicyanomethylides occurred at their 5-positions followed by the elimination of dicyanomethylene to form 5-substituted 1,2,3-triazines. The reaction did not proceed when parent triazines were adopted as the substrates

REDOX PROPERTIES OF SUPEROXIDE WITH 1,2,3-TRIAZINE DERIVATIVES

Abstract 2-Methyl-1,2,3-triazinium iodide 1 and its dihydro derivative 2 were both allowed to react with potassium superoxide to give the same products, triazine dimer 3 and 5 -oxo-triazine 4 . These reactions showed the unique dual reactivities of superoxide.