Olefin cyclopropanation catalysed by novel ruthenium-arene complexes containing phosphines with pendent arenes

Ruthenium-arene complexes containing phosphines with pendent aryl groups [R uCl2(eta(6)-p-cymene)(PCy2(CH2)(3)Ar)]. Ar = C6H5 and 3,5-(CH3)(2)-C6H3 (1 and 3), and the resulting chelating complexes [RuCl2(PCy2(CH2)(3)-eta(6)-Ar )] (2 and 4) mediate the cyclopropanation of olefins with ethyl diazoacetat e. Comparison of the reactivity patterns of these complexes indicates that p-cymene disengagement is likely the key step in the reactions catalysed by non-chelating complexes 1 and 3. (C) 1999 Elsevier Science Ltd. All rights reserved.