The Large-scale Synthesis and Asymmetric Hydrosilylations of CuIPhEt, a C2-symmetric N-heterocyclic Carbene
Author | : Elizabeth Suzanne Spahn |
Publisher | : |
Total Pages | : 228 |
Release | : 2016 |
Genre | : Asymmetric synthesis |
ISBN | : |
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CuIPhEt is a C2-symmetric N-heterocyclic carbene catalyst used in the asymmetric hydrosilylation of a variety of prochiral ketones with good yields and selectivities. The large-scale, five-step synthesis of this carbene has been devised. The second step of the synthetic plan includes a double asymmetric hydrogenation of a 1,1-diaryl alkene -- a traditionally difficult transformation. The procedure for the use of CuIPhEt in asymmetric hydrosilylations has been optimized and used on both the originally published substrate scope and new compounds. This protocol for the hydrosilylation has been applied in a 10 g reduction to create an intermediate for use toward the total synthesis of antascomicin B. A class of 2-ketoazoles was synthesized for use in asymmetric hydrosilylations, but only poor selectivities were observed.