Synthesis of 4-functionalized pyrazoles via oxidative thio- or selenocyanation mediated by PhICl₂ and NH₄SCN/KSeCN

• Jialiang Wu,
• Haofeng Shi,
• Xuemin Li,
• Jiaxin He,
• Chen Zhang,
• Fengxia Sun and
• Yunfei Du

Beilstein J. Org. Chem. 2024, 20, 1453–1461, doi:10.3762/bjoc.20.128

• oxidant. This metal-free approach was postulated to involve the in situ generation of reactive thio/selenocyanogen chloride (Cl–SCN/SeCN) from the reaction of PhICl2 and NH4SCN/KSeCN, followed by an electrophilic thio/selenocyanation of the pyrazole skeleton. Keywords: PhICl2; pyrazoles; selenocyanation

• of efforts to developing efficient thio/selenocyanation approaches [33][34][35][36][37][38][39][40][41]. Specifically, a plethora of synthetic strategies have been reported for the thiocyanation of heteroaromatic compounds including arenes, indoles, carbazoles, pyrroles, and imidazopyridines [42][43

• pyrazoles to give the corresponding thiocyanated pyrazoles (Scheme 1d) [50]. However, to our knowledge, there are only few reports on the electrophilic selenocyanation of heterocycles [51][52][53] including the biologically important pyrazoles. In this regard, it should be highly desirable to develop an

Copper-promoted/copper-catalyzed trifluoromethylselenolation reactions

• Clément Ghiazza and
• Anis Tlili

Beilstein J. Org. Chem. 2020, 16, 305–316, doi:10.3762/bjoc.16.30

• , this species is in an equilibrium with the −SeCF3 anion. As proposed by Hor and Weng, Deng and Xiao also suggested that CuSeCF3 was the active species in the mechanism. In 2016, the group of Rueping described a sequential copper-catalyzed selenocyanation of aryldiazonium salts, followed by