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Synthesis of axially chiral thiazolidine derivatives and their atroposelective reactions

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dc.contributor Ph.D. Program in Chemistry.
dc.contributor.advisor Doğan, İlknur. Erol, Şule. 2023-03-16T11:03:47Z 2023-03-16T11:03:47Z 2012.
dc.identifier.other CHEM 2012 E67 PhD
dc.description.abstract In this study, various axially chiral thiazolidine-4-one and 4-thiones and their corresponding 5-benzylidene derivatives were synthesized in which the N3(sp2)-Carylbond rotation is hindered and used as scaffolds for the preparation of other axially chiral compounds. The aldol reactions were done on 2-arylimino-3-aryl-thiazolidine-4-ones with benzaldehyde at -78 oC and were found to produce sec-carbinols. Intramolecular hydrogen bonding within the aldol products forming a six membered ring enabled the assignment of stereochemistries of the major and minor diastereomers via analysis of the syn and anti3JH,H1H NMR coupling constants. The aldol reactions of axially chiral 5-methyl-2-(o-aryl)imino-3-(o-aryl)-thiazolidine-4-ones were found to proceed via an enolization mechanism and the axially chiral enolate was found to shield one face of the heterocyclic ring rendering atroposelectivity. The atroposelectivities observed at C-5 of the ring varied from 50:50 to 92:8 depending on the size of the ortho substituent. The 2-arylimino-3-aryl-thiazolidine-4-ones were converted to the corresponding 2-arylimino-3-aryl-thiazolidine-4-thiones using Lawesson’s reagent (LR) which were then converted to 5-benzylidinederivatives. The 5-benzylidine-2-arylimino-3-aryl-thiazolidine-4-thiones were used as heterodienes in the [4+2] cycloaddition reactions with norbornene as a dienophile. The reactions with norbornene were found to proceed with 100% exo selectivity with respect to the norbornane skeleton as determined through NMR experiments. Iminophenyl substituted hemiaminals were synthesized by a regio and stereoselective LiAlH4 reduction of 2-arylimino-3-aryl-thiazolidine-4-ones and have been shown to convert of a hemiaminal to an enamine with time and the kinetics of the process has been followed by a time dependent 1H NMR analysis. The compounds which have o-methoxyphenyl were also subjected to demethylation reactions to obtain axially chiral bidentate N,O and O,O compounds.
dc.format.extent 30 cm.
dc.publisher Thesis (Ph.D.)-Bogazici University. Institute for Graduate Studies in Science and Engineering, 2012.
dc.relation Includes appendices.
dc.relation Includes appendices.
dc.subject.lcsh Thiazoles -- Derivatives.
dc.title Synthesis of axially chiral thiazolidine derivatives and their atroposelective reactions
dc.format.pages xxiv, 169 leaves ;

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