Improving Carbene–Copper-Catalyzed Asymmetric Synthesis of α-Aminoboronic Esters Using Benzimidazole-Based Precursors
摘要:
By using a benzimidazole core and N-substitutions to tune the electronic properties of the corresponding N-heterocyclic carbenes, a one-pot protocol for efficient synthesis of alpha-aminoboronic esters without the need of a glovebox was developed in this work. The starting materials for the transformation can also be extended from aldehydes to ketones. An alternative protocol with short reaction time using preformed carbene-copper chloride is also described.
Asymmetric Synthesis of Protected α-Amino Boronic Acid Derivatives with an Air- and Moisture-Stable Cu(II) Catalyst
作者:Andrew W. Buesking、Vlad Bacauanu、Irene Cai、Jonathan A. Ellman
DOI:10.1021/jo500300t
日期:2014.4.18
access to synthetically useful and pharmaceutically relevant α-amino boronic acid derivatives. The Cu(II)-catalyzed reaction is performed on the benchtop in air at room temperature using commercially available, inexpensive reagents at low catalyst loadings. A variety of N-tert-butanesulfinyl imines, including ketimines, react readily to provide α-sulfinamido boronate esters in good yields and with