Titanium tetrachloride-mediated transformation of five- and six-membered cyclic ethers to the corresponding N-aryl-substituted azacycles is conducted in moderate to good yields under mild reaction conditions. Computational studies suggested a mechanism involving a Lewis acid-assisted ring-opening, a seven-membered metallacycle intermediate and a ring-closing process facilitated by direct participation of the metal center.

A computational design was inspired by previous mechanistic studies and the DFT-guided reactions were implemented in the synthesis of secondary allylamines. The participation of titanium imido intermediates facilitated the reaction and the closed transition states in the bond-forming steps rendered exclusive SN2′ substitution products.

A series of organotin 4-methyl-1,2,3-thiadiazole-5-carboxylates and benzo[1,2,3]thiadiazole-7-carboxylates have been synthesized and characterized by NMR (1H, 13C, and 119Sn), IR, and elemental analyses. The structure of the dimeric complex {[(BTHCO2)SnEt2]2O}2 (BTH represents benzo[1,2,3]thiadiazol-7-yl) has been further confirmed by X-ray diffraction crystallography. Assessment for fungicidal activity indicates that all of the newly synthesized compounds exhibit good growth inhibition against Alternaria solani, Cercospora arachidicola, Gibberella zeae, Physalospora piricola, and Botrytis cinerea. High growth inhibition percentage at 50 μg/mL was obtained in vitro in the case of triorganotin 4-methyl-1,2,3-thiadiazole-5-carboxylates and benzo[1,2,3]thiadiazole-7-carboxylates. The corresponding EC50 values of these triorganotin carboxylates have been detected, and values of EC50 as low as 0.12 μg/mL against P. piricola and 0.16 μg/mL against G. zeae, respectively, were observed for triethyltin benzo[1,2,3]thiadiazole-7-carboxylate.