UNEXPECTED DISPROPORTIONATION OF 4,4'-DIALKYLAMINO SUBSTITUTED DIARYLSELENIDES AND TELLURIDES

The unsymmetrical diaryl selenides 1a and b disproportionate under aci dic conditions, to produce the corresponding symmetrical analogues. Si milarly, the aminosubstituted compounds 2b-d and 2k react with 2a to e stablish an equilibrium mixture with high selectivity. Diaryl tellurid es 5a and b also exchange aryl groups, whereas aminosubstituted diaryl sulfides are stable under the reaction conditions. The process, which involves carbon-selenium/tellurium bond cleavage, may involve a free radical mechanism.