TEMPO-Mediated Polyyne Cyclization.

In this work, we report the cyclization of sulfur-linked tetraynes under 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) radical conditions, leading to the formation of novel pentadehydro-Diels-Alder-type addition products. Through this study, we expand the scope of radical-mediated cyclization reactions of polyyne compounds. The results offer new opportunities for the development of radical-based synthetic methodologies.

Utilizing the Pentadehydro-Diels-Alder Reaction for Polycyclic Aromatic Compound Synthesis: Diels-Alder-Based Linker Transformation.

This study introduces a traceless linker strategy for pentadehydro-Diels-Alder (PDDA) cyclization, in which the sulfide/sulfone linker is strategically repurposed as a diene surrogate. As excellent electron-donating dienes, these linkers react with electron-deficient alkenes and alkynes, resulting in a series of highly selective cyclization products. This cascade reaction efficiently integrates the PDDA reaction with linker transformation, formally eliminating the need for permanent structural constraints.

Effectiveness of lime and peat applications on cadmium availability in a paddy soil under various moisture regimes.

In paddy soils, amendments and moisture play important role in the immobilization of cadmium (Cd). The effects of applying lime, peat, and a combination of both on soil Eh, pH, and Cd availability in contaminated soils were investigated under wetted (80 ± 5 % of water holding capacity) and flooded (completely submerged) conditions. In wetted soils, there was little change in Eh, compared to flooded soils where Eh reduced rapidly.