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Title: Homoallylic amine synthesis using phosphine oxides
Author: Armstrong, S. K.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 1992
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This thesis will describe the development of a new route to homoallylic amines 9, in four steps from alcohols 1, or acetals 2, which may themselves have to be synthesised. The synthesis is stereoselective, and generates E-9 and Z-9 quite separately, thereby avoiding the sometimes difficult separation of these isomers. Alkenes 3, readily available from alcohols 1 or acetals 2, undergo regio- and stereo-selective 1,3-dipolar cycloadditions with nitrile oxides 4 or nitrones 6. The resulting heterocycles 5 and 7 are reductively cleaved to give β-hydroxy-δ-aminoalkyldiphenylphosphine oxides 8. These alcohols undergo Horner-Emmons-type elimination of sodium diphenylphosphinite to give homallylic amines 9, stereospecifically. Isoxazolines 5, resulting from nitrile oxide cycloadditions, undergo stereoselective reduction, and give rise to primary amines 9, R3 = H. Isoxazolines 7, resulting from nitrone cycloadditions, give rise to secondary amines 9, R3 = alkyl or aryl. When the alkoxy substituted alkenes 3, R1 = OR are used, protected enol ethers 9, R1 = OR, R3 = Ac are the final products. The vital cycloaddition and reduction steps are both high yielding, although the elimination is often less so.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available