HYDROAMINATION OF ALKENES AND ALKYNES WITH GROUP 2-CENTRED CATALYSTS
Lead Research Organisation:
University of Bath
Department Name: Chemistry
Abstract
The ever-increasing call upon the world's resources demands that chemists devise ever more inventive means to exploit existing and novel chemical feedstocks. The ramifications of so-called sustainable chemistry (also known as 'green chemistry') impact on all stages of the manufacturing process. This includes improving the efficiency of reactions via advances in engineering, catalysis and synthetic chemistry. Atom efficiency or the atom economy concept is an extremely useful tool for rapid evaluation of the amount of waste generated by alternative routes to a specific product. It is calculated by dividing the molecular weight of the desired product by the sum total of the molecular weights of all substances produced in the stoichiometric equation for the reaction(s) involved. This proposal seeks to develop environmentally benign catalysts for the 100% atom efficient transformation of aminoalkenes and -alkynes into valuable heterocyclic compounds. Although this type of transformation is precedented in a series of lanthanide catalysts, our approach utilises the very much understudied, but inexpensive, elements of group 2, the alkaline earths. In exciting preliminary work we have shown that a simple prototype calcium complex is capable of catalysing the cyclisation of a number of substrates with activities far exceeding those reported for more elaborate lanthanide-based species. These studies also highlighted, however, a deficiency of out initial catalyst; its tendency to redistribute to catalytically inactive species over the course of the reaction. We now wish to extend this work with catalysts that will be much less prone to these detrimental processes. These will utilise tripodal borate ligands based upon pyrazole and N-heterocyclic carbene donors. Although the latter class of ligand is almost completely unexplored, further preliminary work has indicated that the strong donor properties of the ligand will prove ideal for the stabilisation of group 2 centres, while the straightforward synthesis also holds promise for the development of new chiral ligands for enantioselective catalysis. Our proposal therefore is an ideal combination of novel academic and applied motivation that will provide an excellent, but challenging, training environment for a capable PhD candidate.
Organisations
People |
ORCID iD |
Michael Hill (Principal Investigator) |
Publications
Arrowsmith M
(2009)
Bis(imidazolin-2-ylidene-1-yl)borate Complexes of the Heavier Alkaline Earths: Synthesis and Studies of Catalytic Hydroamination
in Organometallics
Arrowsmith M
(2009)
A hydride-rich magnesium cluster.
in Angewandte Chemie (International ed. in English)
Arrowsmith M
(2013)
Dearomatized BIAN Alkaline-Earth Alkyl Catalysts for the Intramolecular Hydroamination of Hindered Aminoalkenes
in Organometallics
Arrowsmith M
(2009)
Tris(imidazolin-2-ylidene-1-yl)borate Complexes of the Heavier Alkaline Earths: Synthesis and Structural Studies
in Organometallics
Arrowsmith M
(2010)
Dearomatization and C-H Deprotonation with Heavier Group 2 Alkyls: Does Size Matter?
in Organometallics
Arrowsmith M
(2011)
Suppression of Schlenk Equilibration and Heavier Alkaline Earth Alkyl Catalysis: A Dearomatization Strategy
in Organometallics
Arrowsmith M
(2011)
Cation Charge Density and Precatalyst Selection in Group 2-Catalyzed Aminoalkene Hydroamination
in Organometallics
Barrett A
(2008)
ß-Diketiminato Calcium Acetylides: Synthesis, Solution Dimerization, and Catalytic Carbon-Carbon Bond Formation
in Organometallics
Barrett AG
(2010)
Carbodiimide insertion reactions of homoleptic heavier alkaline earth amides and phosphides.
in Dalton transactions (Cambridge, England : 2003)
Barrett AG
(2009)
Heavier group 2 metals and intermolecular hydroamination: a computational and synthetic assessment.
in Journal of the American Chemical Society
Barrett AG
(2008)
Insertion reactions of beta-diketiminate-stabilised calcium amides with 1,3-dialkylcarbodiimides.
in Dalton transactions (Cambridge, England : 2003)
Barrett AG
(2008)
Reversibility in the protonolysis of a beta-diketiminate stabilised calcium bis(trimethylsilyl)amide with benzylamine.
in Dalton transactions (Cambridge, England : 2003)
Barrett AG
(2009)
Catalytic 2,3,4-hexatriene formation by terminal alkyne coupling at calcium.
in Chemical communications (Cambridge, England)
Barrett AG
(2008)
Heavier group 2 element-catalysed hydroamination of isocyanates.
in Chemical communications (Cambridge, England)
Barrett AG
(2008)
Triazenide complexes of the heavier alkaline earths: synthesis, characterization, and suitability for hydroamination catalysis.
in Inorganic chemistry
Barrett AG
(2009)
Beta-diketiminato calcium and magnesium amides; model complexes for hydroamination catalysis.
in Inorganic chemistry
Brinkmann C
(2012)
Heavier alkaline earth catalysts for the intermolecular hydroamination of vinylarenes, dienes, and alkynes.
in Journal of the American Chemical Society
Brinkmann C
(2012)
Alkaline Earth Catalysis of Alkynyl Alcohol Hydroalkoxylation/Cyclization
in Organometallics
Crimmin M
(2008)
Heavier Group 2 Element Catalyzed Hydrophosphination of Carbodiimides
in Organometallics
Crimmin M
(2010)
Synthesis of ß-diketiminato calcium silylamides and their reactions with triethylaluminium
in New Journal of Chemistry
Crimmin MR
(2008)
Bis(trimethylsilyl)methyl derivatives of calcium, strontium and barium: potentially useful dialkyls of the heavy alkaline earth elements.
in Chemistry (Weinheim an der Bergstrasse, Germany)
Crimmin MR
(2009)
Intramolecular hydroamination of aminoalkenes by calcium and magnesium complexes: a synthetic and mechanistic study.
in Journal of the American Chemical Society
Crimmin MR
(2009)
Beta-diketiminate C-H activation with heavier group 2 alkyls.
in Dalton transactions (Cambridge, England : 2003)
Hill M
(2007)
Alkali and alkaline-earth metals
in Annual Reports Section "A" (Inorganic Chemistry)
Hill M
(2008)
Alkali and alkaline earth metals
in Annual Reports Section "A" (Inorganic Chemistry)
Hill M
(2009)
Alkali and alkaline-earth metals
in Annual Reports Section "A" (Inorganic Chemistry)
Hill MS
(2010)
Calcium-centred phosphine oxide reactivity: P-C metathesis, reduction and P-P coupling.
in Chemical communications (Cambridge, England)
Hill MS
(2010)
Magnesium hydride-promoted dearomatisation of pyridine.
in Dalton transactions (Cambridge, England : 2003)
Hill MS
(2010)
Group 3-centred dehydrocoupling of Me2NH·BH3.
in Chemical communications (Cambridge, England)
Lachs J
(2008)
Heavier Group-2-Element Catalyzed Hydroamination of Carbodiimides
in European Journal of Inorganic Chemistry
Leventis HC
(2010)
Nanostructured hybrid polymer-inorganic solar cell active layers formed by controllable in situ growth of semiconducting sulfide networks.
in Nano letters
Liptrot D
(2010)
Group 2 Promoted Hydrogen Release from NMe 2 H·BH 3 : Intermediates and Catalysis
in Chemistry - A European Journal
Description | This grant allowed us to demonstrate that the sustainable and earth abundant group 2 metals magnesium and calcium could be employed as homogeneous catalysts for a wide variety of carbon-forming catalytic reactions. Taking the hydroamination of alkenes as an initial prototype we demonstrated through a variety of detailed mechanistic studies that these metals could be competitive with established precious metal-based systems. |
Exploitation Route | This work has led to a wide range of academic groups taking up group 2 reagents to carry out catalytic reactions. Although there are not yet any meaningful examples of this chemistry being applied in an industrial context, this is probably a matter of time. |
Sectors | Chemicals Energy Pharmaceuticals and Medical Biotechnology |