Microwave-assisted ring-closing metathesis revisited. On the question of the nonthermal microwave effect.
The ring-closing metathesis reactions (RCM) of six standard diene substrates leading to five-, six-, or seven-membered carbo- or heterocycles were investigated under controlled microwave irradiation. RCM protocols were performed with standard Grubbs type II and a cationic ruthenium allenylidene catalyst in neat and ionic liquid-doped methylene chloride under sealed vessel conditions. Very rapid conversions (15 s) were achieved utilizing 0.5 mol % Grubbs II catalyst under microwave conditions. Careful comparison studies indicate that the observed rate enhancements are not the result of a nonthermal microwave effect.
Garbacia
Stefania
S
Institut de Chimie, UMR 6509 Universite de Rennes 1-CNRS, Campus de Beaulieu, 35042 Rennes, France.
Desai
Bimbisar
B
Lavastre
Olivier
O
Kappe
C Oliver
CO