ABSTRACT
Recently, several novel iridium complexes have been shown to catalyse group transfer reactions in a highly selective fashion. Rhodium complexes, and in particular dirhodium tetracarboxylate salts, have proven to be a remarkably useful class of catalysts for these reactions through several decades of development. Recent results suggest that iridium may offer opportunities to address challenges in this chemistry and provide complementary reactivity patterns. This tutorial review outlines the recent developments in Ir-catalyzed enantioselective group transfer chemistry with highlights on examples which display this unique reactivity.
Subject(s)
Imines/chemistry , Iridium/chemistry , Methane/analogs & derivatives , Catalysis , Cyclopropanes/chemistry , Methane/chemistry , StereoisomerismABSTRACT
A perfect pair: Silanediols are effective catalysts for the addition of silyl ketene acetals to N-acylisoquinolinium ions. Importantly, this is the first example of a silanediol plausibly participating in anion-binding catalysis, a relatively new direction in the field of hydrogen-bond-donor catalysis. The chiral, enantiopure C2 -symmetric silanediol 1 catalyzes enantioselective transformations.
ABSTRACT
Silanediols are introduced as a new class of hydrogen bond donor catalysts for the activation of nitroalkenes toward nucleophilic attack. Excellent yields of product are obtained for the conjugate addition of indole to ß-nitrostyrene catalyzed with a stable, storable dinaphthyl-derived silanediol. The preparation and structural characterization of a C(2)-symmetric chiral silanediol is also reported along with its ability to catalyze the conjugate addition reaction.