Takumi Mizuno

Synthesis of 2,4-dihydroxyquinazolines using carbon dioxide in the presence of DBU under mild conditions

Abstract Chemical fixation of carbon dioxide was performed under mild conditions. Carbon dioxide (1 atm) easily reacted with 2-aminobenzonitriles at 20°C, assisted by DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) to give 2,4-dihydroxyquinazolines in excellent yields.

Facile synthesis of S-alkyl thiocarbamates through reaction of carbamoyl lithium with elemental sulfur

Abstract Efficient synthesis of S-alkyl thiocarbamates was developed. The key step of this synthetic method is a conversion of carbamoyl lithium, generated from lithium dialkylamide and carbon monoxide, to lithium thiocarbamate by addition of elemental sulfur.

Novel synthesis of S-alkyl thiocarbamates from amines, carbon monoxide, elemental sulfur, and alkyl halides in the presence of a selenium catalyst

Abstract Carbonyl selenide easily reacted with elemental sulfur at low temperature to form carbonyl sulfide in a good yield, and reaction of ammonium salts of selenocarbamates with elemental sulfur brought about ready transformation to those of thiocarbamates. On the basis of the high catalytic activity of selenium for carbonylation of amines with carbon monoxide in addition to these important findings, a convenient new method for synthesis of S-alkyl thiocarbamates was developed through the carbonylation of amines with carbon monoxide and elemental sulfur in the presence of a selenium catalyst under mild conditions followed by alkylation of ammonium salts of the thiocarbamates with alkyl halides.

Synthesis of quinazolines using carbon dioxide (or carbon monoxide with sulfur) under mild conditions

Sulfur-assisted carbonylation of 2-aminobenzonitriles with carbon monoxide using K2CO3 as a base under ambient conditions (1 atm, 20°C) to afford 2-hydroxy-4-mercaptoquinazolines in excellent yields was found. This carbonylation was applied to chemical fixation of carbon dioxide under mild conditions. Carbon dioxide (1 atm) easily reacted with 2-aminobenzonitriles at 20°C assisted by 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) to give 2,4-dihydroxyquinazolines in excellent yields.

Selective and one-pot formation of phenols by anodic oxidation☆

Abstract Direct monohydroxylation of benzene and substituted benzenes was successfully performed by anodic oxidation to form the corresponding phenol derivatives in good yields. The anodic oxidation was generally carried out in a mixed solvent of trifluoroacetic acid and dichloromethane containing triethylamine using a divided cell equipped with a platinum plate as the anode, a carbon rod as the cathode. Benzene derivatives having electron withdrawing groups were suitable for the present electrochemical oxidation. It was clarified that aryltrifluoroacetates were formed as the initial products from the reaction of the radical cations, generated by one electron transfer from the substrates, with trifluoroacetic acid, followed by hydrolysis during work-up to give the corresponding phenols.

Synthesis of Aromatic Urea Herbicides by the Selenium-assisted Carbonylation using Carbon Monoxide With Sulfur

Abstract Commercially useful aromatic urea herbicides were synthesized in good yields from lithium amides of aromatic amines with thiocarbamates, which were prepared by the selenium-assisted carbonylation of secondary amines with carbon monoxide and sulfur under mild conditions.

Design of Fullerene Derivatives for Stabilizing LUMO Energy using Donor Groups Placed in Spatial Proximity to the C60 Cage

A series of arylated dihydrofullerene derivatives were synthesized to elucidate the effective design of fullerene derivatives for enhancing the performance of organic photovoltaics. The LUMO energy of the fullerenes was estimated by the first reduction potential and theoretical calculations. The results showed that the methoxy groups substituted at spatial proximity to the fullerene core offered significant stabilization of the LUMO level. The stabilizing effect of the directly arylated fullerenes is more significant than that of conventional methanofullerenes. The theoretical investigation was performed with regard to the electronic interaction between the methoxy and fullerene moieties.

Sulfur-assisted O-carbonylation of alcohols with carbon monoxide in the presence of dbu

Abstract The first example of sulfur-assisted O-carbonylation is described. Alcohols react with carbon monoxide, elemental sulfur, and alkyl halides in the presence of DBU to give S-alkyl carbonothioates selectively in good to excellent yields.

Reductive carbonylation of nitrobenzenes catalyzed by a new binuclear rhodium complex

Abstract The binuclear rhodium complex [(Ph 3 P) 4 Rh 2 (μ-OH) 2 ] · 2C 6 H 6 is an effective catalyst for the reductive carbonylation of nitrobenzenes to carbamate esters. Electron-withdrawing groups at the para-position enhance the reactivity of the substrate in comparison with electron-donating groups.

Regioselective azidomethoxylation of enol ethers by anodic oxidation

Abstract Anodic oxidation of enol ethers 1 in methanol containing sodium azide using a divided cell brought about facile and regioselective azidomethoxylation to give the corresponding acetals 2 of α-azido carbonyl compounds in good yields.