Mechanistic studies are performed on the alkane hydroxylation with m-CPBA (m-chloroperbenzoic acid) catalyzed by nickel(II) complexes, Ni II (L). In the oxidation of cycloalkanes, Ni II (TPA) acts as an efficient catalyst with a high yield and a high alcohol selectivity. In the oxidation of adamantane, the tertiary carbon is predominantly oxidized. The reaction rate shows first-order dependence on [substrate] andThe reaction exhibited a relatively large kinetic deuterium isotope effect (KIE) of 6.7, demonstrating that the hydrogen atom abstraction is involved in the ratelimiting step of the catalytic cycle. Furthermore, Ni II (L) supported by related tetradentate ligands exhibit apparently different catalytic activity, suggesting contribution of the Ni II (L) in the catalytic cycle. Based on the kinetic analysis and the significant effects of O 2 and CCl 4 on the product distribution pattern, possible contributions of (L)Ni II À O * and the aroyloxyl radical as the reactive oxidants are discussed.
Deprotonative formation of biarylazacyclooctynone (BARAC) from the corresponding enol triflate is described. The reaction furnished the azacyclooctynone within one hour at –78 °C. This process could be performed in one pot from the starting ketone to provide a range of BARAC derivatives in moderate to excellent yields. The protocol enabled the gram-scale formation of the BARAC skeleton by reducing the number of reaction steps. Furthermore, the established method was applied to the synthesis of the BARAC derivative bearing a coumarin moiety.
Taste perception is affected by various environmental factors. In the present study, we investigated the effects of visual and aromatic stimulations on stress responses and taste perception. Fourteen young healthy participants were assessed for stress levels and taste intensities under five different conditions: normal (no stimuli), watching an action scene, watching a forest scene, sniffing a rosemary aroma, and sniffing a lavender aroma. Compared to participants under the action scene condition, participants under the forest scene or under the rosemary aroma condition showed significantly lower stress levels. Furthermore, the forest scene condition significantly increased the saltiness intensity, whereas the rosemary aroma condition significantly increased the bitterness intensity. A positive or negative correlation was observed between the stress level and taste intensity of sourness and saltiness, respectively. These findings indicate that visual image and aroma have the potential to change taste perception as well as modulate stress conditions.
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