On the use of tandem allylic acetate isomerisation and ring-closing metathesis with palladium(0) phosphine complexes and ruthenium benzylidenes as orthogonal catalysts

Attempted tandem allylic acetate isomerisation and ring-closing metathesis using combinations of palladium(0)/Grubbs' catalyst/PPh3 led to either allylic isomerisation or ring-closing metathesis but not both in tandem. The effect was traced to deactivation of Grubbs' catalyst by added PPh3 and poisoning of the Pd(0) by the necessarily released PCy3 (Cy=cyclohexyl) from Grubbs' catalyst. Successful tandem isomerisation/ring-closing metathesis was achieved by the use of palladium(0)/PPh3 systems in conjunction with a PCy3 free olefin metathesis catalyst. (C) 2001 Elsevier Science Ltd. All rights reserved.