Comparing neutral (monometallic) and anionic (bimetallic) aluminium complexes in hydroboration catalysis : influences of lithium cooperation and ligand set

Pollard, Victoria A. and Fuentes, M. Àngeles and Kennedy, Alan R. and McLellan, Ross and Mulvey, Robert E. (2018) Comparing neutral (monometallic) and anionic (bimetallic) aluminium complexes in hydroboration catalysis : influences of lithium cooperation and ligand set. Angewandte Chemie International Edition. ISSN 1433-7851 (https://doi.org/10.1002/anie.201806168)

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Abstract

Bimetallic lithium aluminates and neutral aluminum counterparts are compared as catalysts in hydroboration reactions with aldehydes, ketones, imines and alkynes. Possessing Li–Al cooperativity, ate catalysts are found to be generally superior. Catalytic activity is also influenced by the ligand set, alkyl and/or amido. Devoid of an Al−H bond, iBu2Al(TMP) operates as a masked hydride reducing benzophenone through a β‐Η transfer process. This catalyst library therefore provides an entry point into the future design of Al catalysts targeting substrate specific transformations.