New methodology for the organocatalysed α-Amination reaction

Simple item page
dc.contributor.advisorHunter, Rogeren_ZA
dc.contributor.authorMsutu, Ath'enkosien_ZA
dc.date.accessioned2016-01-29T11:04:56Z
dc.date.available2016-01-29T11:04:56Z
dc.date.issued2015en_ZA
dc.descriptionIncludes bibliographical referencesen_ZA
dc.description.abstractResearch into organocatalyzed asymmetric reactions has been a rapidly growing and competitive field in recent times, wherein amino catalysis is widely used for the asymmetric functionalisation of carbonyl compounds. Since its simultaneous publication by List and Jørgensen, the organocatalysed α-amination reaction has become a key method for asymmetric heteroatom functionalisation of carbonyl compounds. Herein we report the first application of this methodology to acetals, with the ultimate goal of applying the methodology to the asymmetric desymmetrisation of bis-acetals as a novel contribution to this growing field. Following extensive optimisation, acidic reaction conditions for the reaction were established in which dibenzyl azodicarboxylate (DBAD) was used as the aminating agent and (S)-(-)-5-(2-pyrrolidinyl)-1H-tetrazole as the preferred organocatalyst. The desired aminated products were obtained in high yields and enantioselectivities. The reaction showed broad substrates cope in its application to ketals, dioxolanes and lactols. A hydrazide N-N bond cleavage methodology was also developed for the aminated products in oxazolidinone form. This methodology is based on Magnus' alkylation / E1CB strategy. The novel contribution here is using ditheyl bromoacetate as an alkylating agent and as a better elimination partner. A range of bis-acetals were synthesised via three synthetic routes using malonate-, sulfone and cyclopentene-based synthesis strategies. The acetal reaction was used for the desymmetrisation of two of these bisacetals as a proof of concept. This is a feat not achieved with the more reactive dicarbonyl analogue.en_ZA
dc.identifier.apacitationMsutu, A. (2015). <i>New methodology for the organocatalysed α-Amination reaction</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Chemistry. Retrieved from http://hdl.handle.net/11427/16608en_ZA
dc.identifier.chicagocitationMsutu, Ath'enkosi. <i>"New methodology for the organocatalysed α-Amination reaction."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Chemistry, 2015. http://hdl.handle.net/11427/16608en_ZA
dc.identifier.citationMsutu, A. 2015. New methodology for the organocatalysed α-Amination reaction. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Msutu, Ath'enkosi AB - Research into organocatalyzed asymmetric reactions has been a rapidly growing and competitive field in recent times, wherein amino catalysis is widely used for the asymmetric functionalisation of carbonyl compounds. Since its simultaneous publication by List and Jørgensen, the organocatalysed α-amination reaction has become a key method for asymmetric heteroatom functionalisation of carbonyl compounds. Herein we report the first application of this methodology to acetals, with the ultimate goal of applying the methodology to the asymmetric desymmetrisation of bis-acetals as a novel contribution to this growing field. Following extensive optimisation, acidic reaction conditions for the reaction were established in which dibenzyl azodicarboxylate (DBAD) was used as the aminating agent and (S)-(-)-5-(2-pyrrolidinyl)-1H-tetrazole as the preferred organocatalyst. The desired aminated products were obtained in high yields and enantioselectivities. The reaction showed broad substrates cope in its application to ketals, dioxolanes and lactols. A hydrazide N-N bond cleavage methodology was also developed for the aminated products in oxazolidinone form. This methodology is based on Magnus' alkylation / E1CB strategy. The novel contribution here is using ditheyl bromoacetate as an alkylating agent and as a better elimination partner. A range of bis-acetals were synthesised via three synthetic routes using malonate-, sulfone and cyclopentene-based synthesis strategies. The acetal reaction was used for the desymmetrisation of two of these bisacetals as a proof of concept. This is a feat not achieved with the more reactive dicarbonyl analogue. DA - 2015 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2015 T1 - New methodology for the organocatalysed α-Amination reaction TI - New methodology for the organocatalysed α-Amination reaction UR - http://hdl.handle.net/11427/16608 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/16608
dc.identifier.vancouvercitationMsutu A. New methodology for the organocatalysed α-Amination reaction. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Chemistry, 2015 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/16608en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Chemistryen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherChemistryen_ZA
dc.titleNew methodology for the organocatalysed α-Amination reactionen_ZA
dc.typeDoctoral Thesis
dc.type.qualificationlevelDoctoral
dc.type.qualificationnamePhDen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
Files
Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
thesis_sci_2015_msutu_ath_039_enkosi.pdf
Size:
3.04 MB
Format:
Adobe Portable Document Format
Description:
Download
Collections
PhD / Doctoral