A borylcopper species generated from bis(pinacolato)diboron and its additions to alpha,beta-unsaturated carbonyl compounds and terminal alkynes

The addition of bis(pinacolato)diboron [(Me2C2O2)B-B(O2C2Me4)] to alpha,bet a -unsaturated carbonyl compounds giving beta -boryl carbonyl compounds and the addition to terminal alkynes yielding either 2-boryl-1-alkenes or 1-bo ryl-1-alkenes were carried out in DMF at room temperature in the presence o f CuCl and AcOK. The transmetalation between diboron and [Cu(CI)OAc]K gener ating a borylcopper species was proposed as the key step in the reactions b ecause CuOAc similarly mediated both addition reactions to enones and alkyn es in the presence of LiCl. (C) 2001 Elsevier Science B.V. All rights reser ved.