Dr. Xiaodong Michael Shi
University of South Florida
Host: Dr. Yu Yuan
Title:
Curiosity Driven New Reactivity Discovery
Abstract:
Homogeneous gold catalysis has been developed explosively during the past decades. Despite the
remarkable electrophilic activation of alkynes by cationic Au(I) catalysts, such as PPh3Au+, one
challenge is to overcome their poor stability at high temperature. However, in order to activate some
less reactive substrates, such as internal alkynes, harsher reaction conditions are usually required.
As a good σ-donor and π-receptor, triazole has been applied as a ligand to improve the stability of
cationic Au(I) catalysts. Taking advantage of the good stability of triazole-Au(I) complexes (TA-Au),
we successfully achieved good reactivity of intermolecular hydroamination for both terminal and
internal alkynes. Unlike previous reported gold catalysts, the TA-Au catalysts activate alkynes
selectively over allenes. With this excellent chemoselectivity, TA-Au catalysts showed interesting
reactivity in propargyl ester and vinyl ether rearrangement. This facilitates the development of otherwise
challenging transformations, for instance, asymmetric synthesis of substituted allenes, Schmittel
cyclization, dienal synthesis, and so on.
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