Development of Practical Methodologies for Co(II) Catalyzed Hydrofunctionalizations
Loading...
Date
2018-05
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
The Ohio State University
Abstract
Catalytic transition metal mediated hydrofunctionalization of readily accessible 1,3-dienes provides synthetic utility for pharmaceutical products and fine chemical synthesis. Historical works have focused on using rare and expensive transition metals that are not as cheap or as earthly abundant at cobalt. Hydrovinylation of olefins is an extensively studied field of hydrofunctionalization. The cobalt-mediated hydrovinylation conditions were adapted to other hydrofunctionalizations such as hydroboration and the heterodimerization of alkyl acrylates and 1,3-dienes. Hydroboration, a more common type of hydrofunctionalization, affords allylic and homoallylic boronate esters. These boronate esters are excellent intermediates for conversion into a variety of functional groups such as amines, alcohols, carbonyls, as well as other boronate species. This research focuses on the reduction of Co(II) to the highly active cationic Co-(I) catalyst to effect high regio- and chemo-selective hydroboration. Using this system, the ligand effects, solvent effects, counter-ion effects, temperature, and the presence or absence of an additive were studied to optimize the efficacy of Co(I). The heterodimerization of alkyl acrylates and 1,3-dienes, a less common type of hydrofunctionalization, affords selective regio-, chemo and enantioselective adducts. This research focuses on more practical, cost-effective and green conditions for the established heterodimerization reaction. These heterodimerized products can further be transformed via Michael Addition reactions for further molecular complexity. The products from both hydrofunctionalization reactions can potentially be useful for the synthesis of intermediates for large scale production of commercially relevant chemicals.
Description
Keywords
organometallic, organic chemistry, chemistry