The relative contents of Cu⁺ and Cu²⁺ in solutions of anhydrous Nieuwland catalyst and CuCl₂-added anhydrous Nieuwland catalyst were detected by X-ray photoelectron spectroscopy (XPS). Results indicated that Cu⁺ could be transformed into Cu²⁺ during the process of acetylene dimerization into monovinylacetylene, leading to deactivation of the catalyst. Moreover, the addition of Cu²⁺ inhibited the oxidation of Cu⁺ into Cu²⁺ and enhanced the performance and lifetime of the catalyst. The optimum molar ratio of Cu⁺ to Cu²⁺ was approximately 2:1; at this ratio, up to 40% acetylene conversion may be achieved.

An efficient NCS-promoted thiocyanation of pyrrolo[1,2-a]quinoxalines with NH₄SCN or KSCN was developed. Moreover, in the presence of KSeCN, the selenocyanation of pyrrolo[1,2-a]quinoxalines was also achieved.

A general, yet efficient synthesis method of 9-arylfluorenes via metal-free reductive coupling of N-tosylhydrazones and arylboronic acids has been developed. This methodology is realized by a one-pot protocol in two steps involving the preparation of N-tosylhydrazones by reacting tosylhydrazide with 9-fluorenone derivatives, followed by the reductive coupling of arylboronic acid in the presence of potassium carbonate to afford various 9-arylfluorenes analogues in moderate to excellent yields. Importantly, the catalytic system presented here enables the use of easily accessible starting materials and can be employed on a wide variety of substrates with good functional group tolerance. This protocol could also be particularly useful for the synthesis of 9-fluorenyl-substituted carbazolyl compounds.

The rapid and efficient KI/H₂O₂-mediated 2-sulfonylation of substituted indoles and N-methylpyrrole was established.