Nickel catalyzed tellurium-zinc exchange reactions. A new preparation of arylzinc reagents

Diaryltellurides 2 and diarylditellurides 3 undergo a smooth tellurium-zinc exchange reaction in the presence of catalytic amounts of Ni(acac)(2) (5-10 mmol %) leading to arylzinc derivatives 1. The reaction can be extended to the preparation of alkylzinc compounds and allows a stereoselective cyclization to a 2,4-disubstituted tetrahydrofuran by a radical ring closure of an unsaturated telluride. (C) 1997, Elsevier Science Ltd.