A base-free copper-assisted synthesis of C₂-symmetric spirotelluranes and biaryls based on divergent stoichiometry of Na₂Te

A one pot Cu(I)-assisted synthetic methodology has been developed for the preparation of biologically important C₂-symmetric spirodiaza, benzyloxy and benzoxytelluranes from 2-bromo-N-aryl benzamides, benzyl alcohols, and benzoic acids by using the tellurium dianion (Te^2-) under base-free conditions. Furthermore, C-C coupled biaryl 1,1'-diamides have been prepared by using an excess of Na₂Te under the same reaction conditions. The synthesized spirodiazatelluranes served as a potent catalyst for the reduction of H₂O₂ and nitro-Michael reactions.