Specificity in the reactions of bis-allyl nickel complexes and the olefin metathesis reaction
Specificity in the reactions of bis-allyl nickel complexes and the olefin metathesis reaction
Reaction of benzaldehyde, acrolein and acetaldehyde with butadiene in the presence of stoichiometric quantities of the a,w -octadiendiyl nickel phosphine complex have been studied. The products formed were in general branched and linear alcohols derived from one mole each of the nickel complex and the aldehyde. The ratio of these products varied both with, the mode of formation of the Ni(O) complex and the associated organophosphine. Attempts to carry out these reactions under catalytic conditions withrespect to the nickel complex were unsuccessful.Reactions of isoprene and acetaldehyde only gave products in a catalyst system derived from Ni(CDT).PR3. Products obtained were both 1:1 and 2:1isoprene to acetaldehyde adducts. The 2:1 adducts were head-tail in nature with the attack of aldehyde occurring almost exclusively at one end of the molecule. This specificity is suggested to be consistent with the hypothesis that electrophiles attack at a a -allylnickel bond in preference to an -allylnickel bond, and is discussed in these terms.Dimerisation of cyclooctene by a tungsten salt was shown to occur by a Lewis acid type mechanism to give cyclooctylidene, although the nature of the species involved is not known. The major part discusses the metathesis of a,w-olefinic esters catalysed by WC16 SnMe4. In these reactions the main products were symmetric olefinic diesters arising from dimerisation with elimination of ethylene. Mixtures of cis and trans-isomers, consistent with thermodynamic considerations were obtained yields were generally 40-50. Olefinic esters with a chain length of less than five carbon atoms inhibited reaction by association and deactivation of the catalyst. These reactions are suggested to involve metal carbene intermediates and the potential of metathesis reactions in organic synthesis has been discussed.
University of Southampton
1976
Crimmin, Michael John
(1976)
Specificity in the reactions of bis-allyl nickel complexes and the olefin metathesis reaction.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
Reaction of benzaldehyde, acrolein and acetaldehyde with butadiene in the presence of stoichiometric quantities of the a,w -octadiendiyl nickel phosphine complex have been studied. The products formed were in general branched and linear alcohols derived from one mole each of the nickel complex and the aldehyde. The ratio of these products varied both with, the mode of formation of the Ni(O) complex and the associated organophosphine. Attempts to carry out these reactions under catalytic conditions withrespect to the nickel complex were unsuccessful.Reactions of isoprene and acetaldehyde only gave products in a catalyst system derived from Ni(CDT).PR3. Products obtained were both 1:1 and 2:1isoprene to acetaldehyde adducts. The 2:1 adducts were head-tail in nature with the attack of aldehyde occurring almost exclusively at one end of the molecule. This specificity is suggested to be consistent with the hypothesis that electrophiles attack at a a -allylnickel bond in preference to an -allylnickel bond, and is discussed in these terms.Dimerisation of cyclooctene by a tungsten salt was shown to occur by a Lewis acid type mechanism to give cyclooctylidene, although the nature of the species involved is not known. The major part discusses the metathesis of a,w-olefinic esters catalysed by WC16 SnMe4. In these reactions the main products were symmetric olefinic diesters arising from dimerisation with elimination of ethylene. Mixtures of cis and trans-isomers, consistent with thermodynamic considerations were obtained yields were generally 40-50. Olefinic esters with a chain length of less than five carbon atoms inhibited reaction by association and deactivation of the catalyst. These reactions are suggested to involve metal carbene intermediates and the potential of metathesis reactions in organic synthesis has been discussed.
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Published date: 1976
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Local EPrints ID: 462528
URI: http://eprints.soton.ac.uk/id/eprint/462528
PURE UUID: c115433e-b184-4226-ba6b-90bff0d4ff19
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Date deposited: 04 Jul 2022 19:15
Last modified: 04 Jul 2022 19:15
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Author:
Michael John Crimmin
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