Takatoshi Ito

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.

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.

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.

Facile synthesis of (S)-beta-hydroxy-beta-trichloromethylated aromatic ketones by the regioselective ring cleavage of chiral beta-trichloromethyl-beta-propiolactone under the Friedel-Crafts conditions

The reaction of enantiomerically pure beta-trichloromethyl-beta-propiolactone (1) as a chiral building block with an aromatic compound in the presence of Lewis acid provided an acylated product with a chiral trichloromethyl carbinol moiety. The acylated product was used as an effective chiral synthon for natural product synthesis such as enalapril of ACE inhibitor

Preparation and use of novel (S)-β-chlorodifluoromethyl-β-propiolactone as a chiral fluorinated building block

Abstract Novel chiral fluorinated building block, (S)β-chlorodifluoromethyl-β-propiolactone with up to >99% ee was prepared using the Lewis acid catalyzed [2+2]cycloaddition of ketene with chlorodifluoroacetaldehyde followed by enzymatic resolution with a lipase. The lactone thus obtained readily underwent the Friedel-Crafts type acylation with aromatic compounds in the presence of a Lewis acid to afford the corresponding chiral β-hydroxy aryl ketones in good yields.

Regioselective ring cleavage of chiral β-trichloromethyl-β-propiolactone with organoaluminum compounds for the synthesis of optically active intermediates

Abstract A novel alkylating ring cleavage reaction of enantiomerically pure β-trichloromethyl-β-propiolactone as a chiral building block with organoaluminum compounds provided ring-opened products with a chiral trichloromethyl carbinol moiety. A product was demonstrated to be used as an effective chiral synthon for the synthesis of chiral bioactive derivatives such as ipsdienol and sodium cilastatin.

Synthesis of Sulfonylurea Derivatives Used as Oral Antidiabetics by the Selenium-Assisted Carbonylation Using Carbon Monoxide with Sulfur

Abstract Sulfonylurea derivatives including useful antidiabetics (Tolbutamide, Chlorpropamide) were synthesized in good yields from benzene-sulfonamides with thiocarbamates in the presence of DBU. Thiocarbamates were prepared by the selenium-assisted carbonylation of primary amines with carbon monoxide, sulfur, and methyl iodide under mild conditions.