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Title: The study of nitrile ylides with conjugation in heterocyclic synthesis
Author: Strachan, Jon-Paul
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1996
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This research concerned with generation and reaction of diene- and triene- conjugated nitrile ylides. The amide precursors were synthesised from readily available reactants via Pd(0) catalysed cross coupling reactions and the nitrile ylides were generated by the 1,3-dehydrochlorination of imidoyl chlorides. Two series of triene-conjugated nitrile ylides were studied; firstly, those in which the α, β:γ, δ bonds were aromatic and then those with an aromatic ring only in the α,β position. The first series reacted via a [3+2] cycloaddition across the olefin double bond, when this was activated towards cycloaddition, to give a dibenz[e,g]indole. The presence of a methyl group at the 2 or 2'-position of the biaryl unit prevented cyclisation, and dimeric products were then observed. When no methyl group was present reaction occurred via 1.7-electrocylisation at the free ortho position of the γ, δ aromatic ring to give dibenz[c,e]azepines. The second series of nitrile ylides in which the γ,δ:ε,ζ double bonds are olefinic cyclised at 0oC to give cyclopropa[c]isoquinolines as primary products. In cases where the terminal double bond was cis these products reacted further by a Cope rearrangement to give 1,4-bridgedisoquinolines. In cases where the terminal double bond was trans the primary product rearranged on heating via a [1,5] carbon shift accompanied by a complex skeletal rearrangement to give an azatetracyclotridecatetraene and to a lesser extent via an equilibration between exo and endo isomers accompanied by a Cope rearrangement to give 1,4-bridgedisoquinolines. The diene-conjugated nitrile ylides cyclised at room temperature to give cyclopropa[c]isoquinolines in a stereospecific reaction. Thermal decomposition of these products involved an equilibration between exo and endo isomers accompanied by ring expansion to give 1H-2-benzazepines or a [1,5]-sigmatropic hydrogen shift to give 1H-isoquinolines or followed another reaction path to give 5H-2-benzazepines.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available