TfOH-Catalyzed Reactions of Aryl Methyl Ketones with Ynamides: Synthesis of 1-Amino-1H-indenes and 2,4-Dienamides.

The efficient synthesis of 1-amino-1H-indenes and 2,4-dienamides was realized via TfOH-catalyzed reactions of aryl methyl ketones with terminal ynamides in two distinct pathways. Aromatic ketones with high electrophilicity underwent [3 + 2] annulation with ynamides to produce 1-amino-1H-indenes, while aromatic ketones with low electrophilicity proceeded under the same conditions to afford 2,4-dienamides. Furthermore, the obtained 1-amino-1H-indenes could be converted into the corresponding 1H-indenes and dihydro-1H-indenes in excellent yields.

Brønsted acid catalyzed Ficini [2 + 2] cycloaddition of ynamides with enones.

Herein, we describe a novel metal-free Brønsted acid-catalyzed Ficini [2 + 2] cycloaddition of ynamides with enones under mild reaction conditions, leading to the formation of various cyclobutenamides in generally good to excellent yields within short reaction times. This work represents the first example of ynamides involved in a nonmetal-catalyzed [2 + 2] cycloaddition with enones.

Annulations of Ynamides with 1,2-Benzisothiazoles to Construct 1,4-Benzothiazepines and 3-Aminoisoquinolines.

Two distinct TMSOTf-catalyzed annulation reactions between ynamides and 1,2-benzisothiazoles have been developed. The direction of the reaction could be easily switched by applying different thermodynamic-controlled conditions. At room temperature, ynamides undergo a [5 + 2] annulation reaction with 1,2-benzisothiazoles to afford 1,4-benzothiazepines, whereas under heating conditions a desulfurizative annulation reaction proceeds well to access 3-aminoisoquinolines. These two protocols provide biologically important 1,4-benzothiazepines and 3-aminoisoquinolines with high efficiency with broad substrate scopes under mild reaction conditions.

TMSOTf-Catalyzed Reactions of N-Arylynamides with Sulfilimines To Construct 2-Aminoindoles and α-Arylated Amidines.

Here, we disclose an efficient TMSOTf-catalyzed C-H annulation of aryl-terminated N-arylynamides with sulfilimines, leading to the practical assembly of various valuable 2-aminoindoles in generally moderate to excellent yields with a broad range of functional groups, while nonaryl terminated N-arylynamides undergo TMSOTf-catalyzed aminative arylation with sulfilimines providing α-arylated amidines.

Substituent effects on the ultraviolet absorption properties of stilbene compounds-Models for molecular cores of absorbents.

The effects of substituent X and Y on ultraviolet (UV) absorption properties of stilbene compounds XPhCHCHPhY (XSBY) were studied both experimentally and computationally from the viewpoint of UV maximum absorption wavelength (λmax) and the corresponding energy (υmax). In the studies, the contribution of substituents on υmax shift was explored. The results show that with increase of electron withdrawing or electron donating ability of X or Y, there is an enhanced electron delocalization of XSBY that leads to bathochromic shift. Computational analyses based on density functional theory were conducted to elucidate the phenomena. It is disclosed that the υmax values are significantly affected by the excited state, though the electronic effect of ground state cannot be ignored. Finally, on the basis of the respective influences of X and Y, a quantitative model, which was proved reliable by the leave-one-out method, was developed to scale the effects of terminal substituents on υmax. According to the model, the effects of substituents X or Y exhibit almost the same action on υmax owing to the symmetric skeleton of the XSBY compounds. The findings provide deep insight into the effects of terminal substituents on UV absorption properties of stilbene compounds, and the derived model enables practical expression of the relationship between substituents and UV absorption.

Influences of zinc oxide nanoparticles on Allium cepa root cells and the primary cause of phytotoxicity.

Zinc oxide nanoparticles (ZnO-NPs) are widely used in consumer products, which have raised concerns about their impact on the human health and environment. In this study, Allium cepa were treated with 5 and 50 µg/mL ZnO-NPs solutions for 12, 24, and 36 h, respectively. The cytotoxic and genotoxic effects of ZnO-NPs in root meristems of Allium cepa cells were characterized by cell membrane integrity, metabolic activity, reactive oxygen species (ROS) accumulation, DNA damage, chromosome aberration, and cell cycle progression. Substantially elevated Zn levels were observed in the cytoplasmic and nuclear fractions, and the accumulation of zinc in the nuclear fraction (up to 9764 µg/g) was one magnitude greater than that in the cytoplasm (up to 541 µg/g). The complexation of Zn2+ with diethylene triamine pentacetic acid (DTPA) was performed to explicate the respective contribution of insoluble particles or Zn2+ to ZnO-NPs toxicity. We found that the inhibition of root growth accounted for 24.2% or 36.1% when the plants were exposed to Zn2+ that released from 5 or 50 µg/mL of ZnO-NPs for 36 h, respectively, whereas the exposure to 5 or 50 µg/mL of insoluble particles resulted in 75.8% or 63.9% of inhibition, respectively. These findings demonstrated that adverse effects exerted not just by Zn2+ released from ZnO-NPs, but also directly from the nanoparticles. These findings contribute to a better understanding of ZnO-NPs cytotoxicity and genotoxicity in plant cells and provide valuable information for further research on the phytotoxic mechanisms of ZnO-NPs.