Potassium tellurocyanate

A versatile route to 3-benzoheteropines has been reported starting from o-phthalaldehyde, including the first preparations of 3-benzarsepines and the parent 3-benzothiepin and 3-benzoselenepins <96CC2183>. l,7-Dihydro-l//-dibenzo[c,c]tellurepin has been prepared from 2,2 -bis(bromomethyl)biphenyl and potassium tellurocyanate and its complexes with palladium and ruthenium species have been studied, a number of mono- and binuclear complexes are formed <96RTC427>. 

Another method that uses arenediazonium fluoroborates to prepare diaryl tellurides is the reaction with potassium tellurocyanate. Aryl teUurocyanides are postulated as intermediates. 

Another approach to aryl tellurides involving nucleophilic tellurium species consists in the use of aryldiazonium salts as substrates. Arenediazonium tetrafluoroborates 64 react with sodium telluride,128 potassium tellurocyanate 65, sodium 0,0-diethylphosphorotellurolate 66, or aryl tellurolate 2 to give the corresponding diaryl tellurides 3 in moderate yields (Scheme 33).129,130... 

Potassium tellurocyanate, prepared from potassium cyanide and tellurium in DMSO, reacts with benzyl halides to produce benzyl tellurium cyanides in good yields. Because of the sensitivity of potassium tellurocyanate to oxygen and of some of the benzyl tellurium cyanides to light, the reactions must be carried out in an inert atmosphere (nitrogen or argon) under red light. 

Arenediazonium tetrafluoroborates react with potassium tellurocyanate in DMSO. The expected aryl tellurium cyanides are seldom stable enough to be isolable and are converted to diaryl ditellurium compounds. Only 2-nitrophenyl tellurium cyanide and 2,6-dimethyl-phenyl tellurium cyanide were obtained through chromatographic separation from the diaryl ditellurium compounds6. 

Azulenyl tellurium cyanide was synthesized from potassium tellurocyanate and azulene7. 

Diaryl tellurium compounds can be obtained in moderate yields from potassium tellurocyanate and arenediazonium tetrafluoroborates in DMSO at room temperature. The potassium tellurocyanate is obtained from tellurium and potassium cyanide in DMSO. Aryl tellurium cyanides are probably formed as intermediates that disproportionate to the diaryl tellurium products and tellurium dicyanide2. 

Synthesis of the racemic cyclic telluride (2,7-dihydro-17/-dinaphthoR,i ]tellurepin 78), possessing a C2 axis, was based on the reaction of 2,2 -bis(chloromethyl)-l,10-binaphthalene 109 with potassium tellurocyanate in dry DMSO. Reaction of 109 with iodide gave the diiodo derivative (Scheme 7) <2004JOM(689)2377, 1996RTC427>. 

Aryltelluroformates (533), accessible from the corresponding chloroformates, undergo cleavage of the acyl-tellurium bond on photolysis. In the presence of diphenyldiselenide, the oxyacyl radical (534) is trapped as the corresponding alkyl (phenylseleno)formate (535) in excellent yield. Irradiation of aryl bromides or iodides (536) with potassium tellurocyanate (537) in dimethyl sulfoxide, as both solvent and methyl source, yields aryl methyltellurides (538) in modest yields (9-34%). ... 

Aromatic tellurocyanates are prepared by the cyanation of metal tellurolates [66] and aliphatic tellurocyanates can be obtained by alkylation of potassium tellurocyanates (Scheme 15.23) [67]. 

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