Synthesis of diterpenoid precursors via pye allyl nickel complexes
Synthesis of diterpenoid precursors via pye allyl nickel complexes
The preparation and isolation of Cyolododecatriene nickel is reported.Its reaction with isoprene has been shown to exclusively afford 2,6,11trimethyl- x,co bis-lf-allyl-dodecatriendiyl nickel in an essentially quantitative yield. The potential use of this bis-tr-allyl nickelcomplex as an intermediate in the formation of known and novel diterpenoid skeletons via its reactions with olefins and acetylenes has been investigated.Insertion was observed when acetylenes possessing electron withdrawing groups were added to the complex, and the resulting products were shown to be dependent on the workup procedure used to terminate the reaction. When sulphur was employed, the novel diterpenoid precursor 1,2-dimethyl4,8,13-trimetivlcyolotetradeca-cc t.tst-1,4.,8,12 tatraene-1,2-d1carboxylate was obtained with a selectivity of approximately 90%. Carbonylation at -78°C resulted in a mixture of products, the main isomers of which (9oI) were derived from the rearrangement of the terminal isoprene in the C12 chain. No ketonic products resulting from the insertion of carbon monoxide were obtained. The products were shown to result from mixtures of either complete head to tail, or tail to tail and head to, head coupling of the three diene units.The formation of a stable nickel mono-carbonyl species is postulated,' and a reaction mechanism which explains the product distribution is given.The reactions of the bis-it-allyl nickel species with dimethyl acetylenedicarboxylate in the presence of additional weak liganda has been investigated. When 2,6-lutidine was employed, the formation of 2:1 isoprene : acetylene adducts were observed.The intermolecular dimerization of nickel allyl bromides, under the influence of sulphur has been investigated. In all cases, high yields (85,19 - 100%) of coupled product were obtained. The application of the coupling reaction to the synthesis of a diterpenoid precursor has been initiated, and the synthesis of the dibromide precursor to 4,8,12trimethylcyclotetradeca-3,7,11-triene-l -one is given.
University of Southampton
1979
Kelly, Michael Gerard
(1979)
Synthesis of diterpenoid precursors via pye allyl nickel complexes.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The preparation and isolation of Cyolododecatriene nickel is reported.Its reaction with isoprene has been shown to exclusively afford 2,6,11trimethyl- x,co bis-lf-allyl-dodecatriendiyl nickel in an essentially quantitative yield. The potential use of this bis-tr-allyl nickelcomplex as an intermediate in the formation of known and novel diterpenoid skeletons via its reactions with olefins and acetylenes has been investigated.Insertion was observed when acetylenes possessing electron withdrawing groups were added to the complex, and the resulting products were shown to be dependent on the workup procedure used to terminate the reaction. When sulphur was employed, the novel diterpenoid precursor 1,2-dimethyl4,8,13-trimetivlcyolotetradeca-cc t.tst-1,4.,8,12 tatraene-1,2-d1carboxylate was obtained with a selectivity of approximately 90%. Carbonylation at -78°C resulted in a mixture of products, the main isomers of which (9oI) were derived from the rearrangement of the terminal isoprene in the C12 chain. No ketonic products resulting from the insertion of carbon monoxide were obtained. The products were shown to result from mixtures of either complete head to tail, or tail to tail and head to, head coupling of the three diene units.The formation of a stable nickel mono-carbonyl species is postulated,' and a reaction mechanism which explains the product distribution is given.The reactions of the bis-it-allyl nickel species with dimethyl acetylenedicarboxylate in the presence of additional weak liganda has been investigated. When 2,6-lutidine was employed, the formation of 2:1 isoprene : acetylene adducts were observed.The intermolecular dimerization of nickel allyl bromides, under the influence of sulphur has been investigated. In all cases, high yields (85,19 - 100%) of coupled product were obtained. The application of the coupling reaction to the synthesis of a diterpenoid precursor has been initiated, and the synthesis of the dibromide precursor to 4,8,12trimethylcyclotetradeca-3,7,11-triene-l -one is given.
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Published date: 1979
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Local EPrints ID: 462440
URI: http://eprints.soton.ac.uk/id/eprint/462440
PURE UUID: 8eb68daa-fb1c-456e-b7d1-99bef0f3ec6d
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Date deposited: 04 Jul 2022 19:08
Last modified: 04 Jul 2022 19:08
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Author:
Michael Gerard Kelly
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