January 2022

Mechanochemical synthesis of 2,5-disubstituted 1,3,4-oxadiazoles was developed as an environmentally benign alternative to conventional solvent-based methods. In the presence of triphenylphosphine and trichloroisocyanuric acid, N-acylbenzotriazoles condense with acylhydrazides leading to oxadiazoles derivatives in good to excellent yields within minutes. The approach circumvents the need for strictly anhydrous conditions, external heating, long reaction times, as well as tedious multistep procedures. A range of substrates with reactive functionalities was also well tolerated.

The constitutional challenge of an electrostatically directed meta borylation of sterically biased and unbiased substrates is summarized in the present work. The borylation follows an electrostatic interaction between the partially positive and negative charges of the ligand and substrate, respectively. Using our developed strategy, it has been demonstrated that a wide range of challenging substrates, especially 4-substituted substrates can be borylated at the meta position with excellent selectivity. Moreover, unsubstituted substrates are also displayed excellent meta selectivity. The reaction employs bench-stable ligand, proceeds at moderate reaction temperature (40–80 °C), precluding the need to synthesize bulky and sophisticated ligand/template.