SubstrateSelective Catalysis Controlled by BowlShaped Ligands

1
Substrate-Selective Catalysis Controlled by
Bowl-Shaped Ligands
Anthony R. Chianese Department of
Chemistry Colgate University
Iridium complexes of the formula
IrCl(1,5-cyclooctadiene)Gn were synthesized (n
0,1,2). The complexes are active catalysts for
ketone hydrosilylation. Competition experiments
were performed to compare the reactivity of
ketones of varying size
A series of new N-heterocyclic carbene ligands
was synthesized, with side groups composed of
phenylene-bridged dendrimers
By comparing initial rates of conversion, it is
evident that the G2 catalyst is moderately
specific for acetophenone (1) over larger
substrates. For competitive hydrosilylation of 1
vs. 4, 1 reacts 3.7 times more quickly. Using the
control G0 catalyst, this ratio is 1.8
Substrate Specificity