Carboxylate lability as a factor in the Rh2(carboxylate)4-catalysed cyclopropenation and cyclopropanation of alkynes and alkenes.
The mechanism of Rh(2)(carboxylate)(4)-catalysed cyclopropenation and cyclopropanation via two different pathways has been investigated computationally. The two pathways either (a) conserve the Rh(2)O(8) framework, with initial coordination of CH(2)N(2) and further reaction occurring at an axial acceptor site, or (b) allow dechelation of carboxylate to liberate an equatorial site for activation of bound CH(2)N(2.) Calculations on the system in question [Rh(2)(formate)(4), CH(2)N(2), C(2)H(4) or C(2)H(2)] show that both pathways are equally favoured. The importance of coordinated solvent in determining the reaction pathway is demonstrated.
Howell
James A S
JA
School of Chemistry and Physics, Lennard Jones Laboratories, Keele University, Keele, Staffordshire, UK. j.a.s.howell@keele.ac.uk