Diazo-Transfer Reaction of Nonactivated Ketones with 2-Azido-1,3-bis(2,6-diisopropylphenyl)imidazolium Hexafluorophosphate (IPrAP).

The diazo-transfer reaction of nonactivated ketone under mild reaction conditions was developed. Various nonactivated ketones such as aryl methyl ketones, -alkyl methyl ketones, and cyclic ketones were transformed into their corresponding α-diazoketones in one step by treating 2-azido-1,3-bis(2,6-diisopropylphenyl)imidazolium hexafluorophosphate (IPrAP) in the presence of PrNH in ethylene glycol. In the reaction of IPrAP with -alkyl methyl ketone and -alkyl aryl ketones, migratory amidation proceeded under the reaction conditions to afford the corresponding amides.

Syntheses of Aryl Thioethers via Aromatic Substitution of Aryl Halides at 0 to 25 °C.

In this study, we developed mild conditions for the synthesis of an aryl thioether via aromatic substitution using aryl halides, which is a process that has rarely been studied. Aromatic substrates such as aryl fluorides activated with a halogen substituent are difficult to use for substitution reactions, but by using 18-crown-6-ether as an additive, these were successfully converted to their corresponding thioether products. Under the conditions we established, in addition to a wide variety of thiols, less-toxic and odorless disulfides could be used directly as nucleophiles at 0 to 25 °C.

Perceptual simultaneity range for two dichotically presented pure tones with frequency separation below 0.5 Bark.

The perceptual simultaneity range for two diotically presented tones increases with decreasing frequency separation of the two tones from approximately 0.5 Bark. As the present study of two frequency regions shows, this effect is not observed when the two tones are not presented to the same ear, i.

Etherification via Aromatic Substitution on 1,3-Disubstituted Benzene Derivatives.

In this study, we developed a method for etherification via aromatic substitution at the ipso-position of an electron-withdrawing group (EWG) that exists at the meta-position of another EWG. To heighten the reactivity of the substitution reaction, we added a -BuOK solution in tetrahydrofuran (THF) to a mixture of an aromatic substrate, an alcoholic nucleophile, and 18-crown-6-ether in dimethylformamide (DMF), which proved to be a particularly effective sequence. Under the conditions we established, aromatic substrates that are difficult to use for substitution reactions such as aryl fluorides activated with either a bromide or a chloride substituent were aptly converted to corresponding ether products at 25 °C.

Aryl Ether Syntheses via Aromatic Substitution Proceeding under Mild Conditions.

In this study, mild conditions for aromatic substitutions during the syntheses of aryl ethers were developed. In the reaction conditions, the choices of solvent, base, and the sequence for the addition of the reagents proved important. A wide variety of alcohols were used directly as nucleophiles and smoothly reacted with aryl chlorides that possessed either a nitro or a cyano group at either the ortho- or para-position.