Satoru Ito

Ruthenium-catalyzed oxidation of phenols with hydrogen peroxide

Abstract RuCl3 catalyzed the oxidation of trimethylphenol with 30% H2O2 in acidic medium to give the corresponding p-benzoquinone in high yield.

SPECIFIC PHOTOCOUPLING OF 5-BROMOURIDINE TO TRYPTOPHAN IN AQUEOUS FROZEN SOLUTION§

Abstract—5‐Bromouridine (BrUd) photochemically reacted with l‐tryptophan (trp) only in aqueous frozen solution giving rise to 2‐[1,2,3,4‐tetrahydro‐1‐(β‐d‐ribofuranosyl)‐2,4‐dioxo‐5‐pyrimidinyl]‐l‐tryptophan (1a). Under similar conditions irradiation of 5‐bromouracil (BrU) and trp gave the corresponding coupled product 2. Addition of acetone, potassium carbonate or sodium chloride to the frozen system completely inhibited the photocoupling reaction. These photocoupling reactions are suggested to proceed via mixed aggregate formation between trp and BrUd (or BrU) in frozen aqueous solution. Stacking interactions in these aggregates are characterized by an efficient quenching of trp fluorescence by BrUd. Under the same conditions other amino acids such as phenylalanine, tyrosine, histidine and lysine did not react with BrUd, indicating that the photocoupling of BrUd (or BrU) is specific for trp.

A simple synthesis of fluorescent uridines by photochemical method

Abstract A strongly fluorescent 5-pyrenyluridine was prepared by the photoreaction of 2′,3′-0-isopropylidene-5-iodouridine with pyrene. Several fluorescent analogues of uracil were synthesized by similar procedures.

Ruthenium-Catalyzed Aerobic Oxidation of Pantoyl Lactone to Ketopantoyl Lactone

Abstract Pantoyl lactone was selectively oxidized into ketopantoyl lactone with molecular oxygen by the catalysis of ruthenium.

FeCl3-catalyzed oxygenation of 2-halocyclohexanones to adipic acid diesters

Abstract Ferric chloride-catalyzed aerobic oxygenation of 2-halocyclohexanones in methanol to yield adipic acid dimethyl esters.

Photoinduced cross-coupling reaction of 5-bromo-1,3-dimethyluracil to electron-rich aromatics

Abstract On irradiation with Pyrex-filtered light, 5-bromo-1,3-dimethyluracil 1 coupled with methyl- and methoxynaphthalenes 2–7 to give 5-naphthyl-1,3-dimethyluracils 8–13. No coupling product was formed by triplet sensitization except in the cases of 2,3-dimethioxynaphthalene 3 and 2-methoxynaphthalene 5. indicating that the singlet excited states of the naphthalenes are involved in the unsensitized coupling reaction. The kqτ values of the fluorescence quenching of 1,4-dimethoxynaphthalene 2 and 1-methoxynaphthalene 4 by 1 in acetonitrile were comparable with those obtained from the kinetics of the coupling reactions. On the basis of this fact and the fluorescence-quenching rate constants kq in acetonitrile ranging from 108 to 109 M−1 sec−1, involvement of an electron-transfer process possibly via a singlet exciplex is proposed for this cross-coupling reaction.

Triplet-mediated coupling of 5-bromo-1,3-dimetrhyluracil to Nb-methoxycarbonyltryptamine involving a double electron transfer☆

On acetone-sensitization, 5-bromo-1,3-dimethyluracil (1 reacts with Nb-methoxycarbonyltryptamine (4 under the assistance of an electron carrier such as 2-methoxynaphthalene to give a coupling product 6. A mechanism involving a double electron transfer via the triplet state of 1 is proposed.

Photochemical addition of L-lysine to 1,3-dimethyl-4-thiouracil.

Irradiation of an aqueous solution of 1,3‐dimethyl‐4‐thiouracil (1) in the presence of l‐lysine (2) with a high‐presure mercury lamp through a Pyrex filter gave a 1:1 mixture of two photoproducts. One of the products was isolated in a pure form, which on treatment with acetic anhydride‐pyridine yielded the starting material 1. Based on the spectral data (1H and 13C NMR) and the chemical reaction, the structure of the photoproduct was assigned to 3. The photochemical reaction is considered as a nucleophilic addition of l‐lysine to photoexcited 1.

Photochemical reaction of 8-azaxanthine with nucleophiles

Abstract Photolysis of 1,3,7-trimethyl-8-azaxanthine (1) in the presence of primary and secondary alkylamines gave 6-alkylamino-5-methylamino-1,3-dimethyluracils (2) , whereas irradiation of 1 in methanol yielded 5-hydroxy-6-methoxy-1,3-dimethyluracil (3) .