Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Development of Lewis acid mediated stereoselective synthesis of nitrogen containing heterocycles
KTH, Superseded Departments, Chemistry.
2003 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

This thesis deals with the development of syntheticmethodologies for the preparation of enantio- anddiastereomerically enriched nitrogen-containingheterocycles.

Asymmetric Lewis acid mediated Diels-Alder reactions with2H-azirines as dienophiles have been studied.Diastereoselective reactions with enantiomerically pureauxiliary-derived 2H-azirines afforded substituted bi- andtri-cyclic azaheterocycles comprising a fusedtetrahydropyridine–aziridine moiety in high yields andselectivities. It was found that the 8-phenylmenthol auxiliarywas superior to Oppolzer’s bornane-2,10-sultam in thesereactions. The influence of various Lewis acids on the reactionoutcome was probed and their presence was crucial forsuccessful reactions. The novel enantioselectiveaza-Diels-Alder reaction of benzyl- 2H-azirine-3-carboxylatewas investigated with a range of chiral Lewis acids andprovided the corresponding cycloadducts in moderate to lowyields and selectivities. The 2H-azirines were synthesized fromthe corresponding acrylates via the vinyl azides. An improvedand general procedure for thermolysis of vinyl azides into2Hazirines was developed.

Lewis acid mediated radical cyclizations of substitutedN-chloro-4-pentenyl- and 4- hexenylamines gave thecorresponding pyrrolidines in high yields and in moderate tohigh diastereoselectivities. The reactivity andstereoselectivity were found to be strongly influenced by thesubstituents on the alkenylamine. On the other hand, noapparent correlation between the different Lewis acids appliedand the obtained selectivities was observed. The relativestereochemistry of the cyclic products could be predicted usingthe Beckwith-Houk stereochemical model. The pyrrolidines wererearranged via aziridinium ions, which were ring-opened to thecorresponding piperidines. The efforts to developenantioselective radical cyclizations of cationic aminylradicals proved unsuccessful. Reaction conditions and chiralLewis acids were varied, yet, racemic product mixtures wereobtained. The N-chloro-N-alkenylamines were synthesized in goodyields.

Keywords:diastereoselective, enantioselective,alkaloid, Lewis acid, chiral ligand, hetero-Diels-Alderreaction, 2H-azirine, aziridine, tetrahydropyridine, chiralauxiliary, vinyl azide, radical cyclization, cationic aminylradical, pyrrolidine, piperidine, aziridinium ion,N-chloro-N-alkenylamine.

Place, publisher, year, edition, pages
Stockholm: Kemi , 2003. , 61 p.
Series
Trita-IOK, ISSN 1100-7974 ; 2003:82
Keyword [en]
organic chemistry
Identifiers
URN: urn:nbn:se:kth:diva-3588ISBN: 91-7283-570-2 (print)OAI: oai:DiVA.org:kth-3588DiVA: diva2:9409
Public defence
2003-09-19
Note
NR 20140805Available from: 2003-09-08 Created: 2003-09-08Bibliographically approved

Open Access in DiVA

fulltext(404 kB)2218 downloads
File information
File name FULLTEXT01.pdfFile size 404 kBChecksum MD5
02af03c7ae0baf208d849d054524af68ea0696e5a5a3cced1ea82fc649823a74c4e3a0cf
Type fulltextMimetype application/pdf

By organisation
Chemistry

Search outside of DiVA

GoogleGoogle Scholar
Total: 2218 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 456 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf