J. Howarth et K. Gillespie, INVESTIGATIONS INTO THE USE OF NIOBIUM AND TANTALUM COMPLEXES AS LEWIS-ACIDS, Tetrahedron letters, 37(33), 1996, pp. 6011-6012
The Lewis acidity of niobium and tantalum compounds has been studied w
ith respect to simple Diels-Alder reactions. The results show that the
se compounds have excellent Lewis acidity. Copyright (C) 1996 Elsevier
Science Ltd