Revisiting the relationship between business conditions, climate policy uncertainty, and environmental pollution: evidence from the USA.

This paper aims to revisit the interdependency between business conditions, climate policy change, and the environmental pollution of the USA. Interestingly, our paper represents a completion to the existing literature on three levels at least. First, we propose to analyze this issue during normal periods and periods of turmoil, particularly the COVID-19 outbreak. To do so, contrary to previous studies that used economic growth, we employ the ADS index as a real-time business conditions measurement. Second, we employ a frequency approach, based on the continuous wavelet transform, allowing us to understand the nature of the relationship. Understanding whether the relationship holds in the short- or long-term is useful for policymakers in monitoring public policies to achieve CO2 emission reduction as well as to investors interested in high value-added projects. Our analysis shows that, during the last two decades, the relationship between business conditions as well as climate uncertainty index and CO2 emissions is observed during the long- and short-term, and driven through economic conditions. However, during the crisis periods, the effect is detected across various scales and the relationship is bi-directional. Our results have several practical implications for the US policymakers to consider when setting policies for fighting pollution emissions and environmental protection.

Palladium-Catalyzed C-H Bond Functionalization of 6,6-Diphenylfulvenes: An Easier Access to C1-Arylated and C1,C4-Diarylated Fulvenes.

Conditions allowing the palladium-catalyzed regioselective direct arylation of fulvene derivatives are reported. The nature of the aryl source exhibits an important influence on the yield. The reaction of fulvenes with aryl bromides gave poor yields, whereas the use of benzenesulfonyl chlorides gave rise to fulvenes arylated at C1- and C4-positions on the 5-membered ring in good yields. The reaction tolerates various substituents such as nitrile, nitro, fluoro, trifluoromethyl, chloro, or even bromo on the benzenesulfonyl chloride.

Regiocontroled Pd-catalysed C5-arylation of 3-substituted thiophene derivatives using a bromo-substituent as blocking group.

The use of a bromo-substituent as blocking group at the C2-position of 3-substituted thiophenes allows the regioselective introduction of aryl substituents at C5-position via Pd-catalysed direct arylation. With 1 mol % of a phosphine-free Pd catalyst, KOAc as the base and DMA as the solvent and various electron-deficient aryl bromides as aryl sources, C5-(hetero)arylated thiophenes were synthesized in moderate to high yields, without cleavage of the thienyl C-Br bond. Moreover, sequential direct thienyl C5-arylation followed by Pd-catalysed direct arylation or Suzuki coupling at the C2-position allows to prepare 2,5-di(hetero)arylated thiophenes bearing two different (hetero)aryl units in only two steps. This method provides a "green" access to arylated thiophene derivatives as it reduces the number of steps to prepare these compounds and also the formation of wastes.