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|Title:||Studies of intramolecular aziridination using 3-acetoxyaminoquinazolinones|
|Authors:||Draycott, Richard D.|
|Presented at:||University of Leicester|
|Abstract:||A general strategy was devised for the conversion of ,-unsaturated acids into - or -amino acid enantiomers via intramolecular aziridination of the acid double bond as the key step.;The initial step involved tethering of the acid as its acid chloride to the -hydroxy group of a 2-(-hydroxyalkyl)-3-amino-quinazolin-4(3H)-one (QNH2 compounds). although competitive O- and N-acylation was observed in the acylation reactions using 2-(1-hydroxyethyl)-3-aminoquinazolin-4(3H)-one as a model compound, all other QNH2 compounds examined underwent highly chemoselective O-acylation.;Cinnamoylation of a series of 2-(-hydroxyalkyl) QNH2 compounds (alkyl = n-propyl, n-butyl or n-pentyl) followed by intramolecular aziridination via the corresponding QNHOAc intermediates was carried out to identify the optimum length for the tether. In the presence of hexamethyldisilazane, the best yield (95%) was obtained with 6 atoms in the tether using 2-(4-hydroxybut-1-yl)3-aminoquinazolin-4(3H)-one. In the presence of trifluoroacetic acid good yields of the corresponding ring-opened aziridine (benzylic) alcohols were obtained with the 2-(4-hydroxypropyl)- and 2-(5-hydroxypentyl)-3-aminoquinazolin-4(3H)-ones.;To examine the diastereoselectivity in the 6-atom tethered intramolecular aziridination, three racemic 2-(4-hydroxy-2-oxa-1-substituted butyl)-QNH2 compounds were prepared bearing a phenyl, isopropyl, or methyl as the 1-substitutent. Intramolecular aziridination of the O-cinnamoyl, O-tiglyl or O-3,3-dimethylacryloyl esters in the phenyl-substituted cases gave in each case, a single aziridine diastereoisomer in high yield.|
|Rights:||Copyright © the author. All rights reserved.|
|Appears in Collections:||Theses, Dept. of Chemistry|
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