M.Sc. Chemistry
http://hdl.handle.net/10464/2245
2024-03-19T18:33:31ZSynthetic Approaches to C-1 Derivatives of Pancratistatin
http://hdl.handle.net/10464/15076
Synthetic Approaches to C-1 Derivatives of Pancratistatin
Uppalapati, Bhavana
The contents of this thesis describe a synthetic approach towards C-1 derivatives of pancratistatin, utilizing a previously published pathway to access a late-stage cis-diol. The key steps of the approach include enzymatic dihydroxylation to provide the C-ring backbone, Myers’ transposition to convert an allylic alcohol into an olefin, and nucleophilic substitution of a tosylate to insert carbon-based nucleophiles at C-1. Experimental and spectral data are provided for the novel compounds.
Hydroamidation of Vinyl Ethers by Acid-Catalyzed Multicomponent Isocyanide Addition
http://hdl.handle.net/10464/15055
Hydroamidation of Vinyl Ethers by Acid-Catalyzed Multicomponent Isocyanide Addition
Carlson, Brenden Matthew
Hydroamidation of carbon–carbon double bonds is an attractive strategy for installing nitrogen functionality into molecular scaffolds and, with it, increasing molecular complexity. To date, metal-based approaches have dominated this area of chemical synthesis despite the drawbacks of air and moisture sensitivity, limited functional group tolerance, toxicity, and/or high cost often associated with using metals. Herein is enclosed an operationally simple, metal-free, one-pot, regioselective, multicomponent synthetic procedure for the hydroamidation of carbon–carbon double bonds. This method features mild reaction conditions and utilizes isocyanides and vinyl ethers for the rapid and modular synthesis of α-oxygenated amide scaffolds. Additional effort was put towards synthesizing reactive natural products as substrates to the developed methodology, and drafting a probable catalytic cycle for the main and side reactions present within this multicomponent procedure.
Synthesis and Evaluation of Trans-bilayer Cross Linking Phospholipids Based on Click (Azide-Alkyne) Chemistry
http://hdl.handle.net/10464/15024
Synthesis and Evaluation of Trans-bilayer Cross Linking Phospholipids Based on Click (Azide-Alkyne) Chemistry
Hosseini, Yasaman
This thesis describes the synthesis of two phosphatidylcholine (PC) derivatives that are capable of coupling with each other from the alkyl chain through click reaction to form bola-PC. Successful coupling of monomeric phosphatidylcholine derivatives would lead to synthesis of corresponding phosphatidylinositol molecules as future work. PC derivatives that were synthesized in this work were phosphatidylcholine containing terminal azide and terminal alkyne on the alkyl chain of sn2 position. Sn-glycero-3-phosphocholine (GPC) was used as glycerol back bone with two available hydroxyl groups for esterification. The first esterification was done using dibutyltin oxide as catalyst and palmitoyl chloride as acylating agent on the primary hydroxyl group, sn1 position. Secondary hydroxyl group in the sn2 position of GPC was esterified by terminal alkyne and terminal azide fatty acids through Steglich esterification. PC analogues with suitable functional groups for click chemistry were, then, incorporated in the 100 nm-vesicles in buffer solution and exposed to copper catalyst/L-histidine complex and sodium ascorbate solution at room temperature. Formation of bola-PC were observed in the hydrophobic core of lipid bilayer and this was the main objective of this study.
N–Phenyl Pyrroloimidazolone Derivatives for Stereoselective Birch Reduction-Alkylation and Chiral Imidazolylidene-Iridium Complexation
http://hdl.handle.net/10464/14973
N–Phenyl Pyrroloimidazolone Derivatives for Stereoselective Birch Reduction-Alkylation and Chiral Imidazolylidene-Iridium Complexation
Tran, Ngan
This thesis describes the synthesis and use of an N– based proline–derived directing group towards the Birch reduction, diastereoselective alkylation, and the synthesis of NHC–iridium complexes that are precursors for the study of intramolecular aryl C–H activation. A pair of ortho–benzoate esters containing epimeric pyrroloimidazolone chiral auxiliaries underwent sequential Birch reduction and diastereoselective alkylation to provide products ranging from a 50:50 to 95:5 dr for the anti– epimer, and 88:12 to >95:5 diastereomeric ratio (dr) for the syn– epimer. Single crystal X–ray analysis of key anti–epimer–derived products, along with the comparison of the optical rotation measurements of enantiomers that were prepared from the syn–or anti– starting materials to its known enantiomer confirmed the stereoselectivity of the products. This work includes related Schultz stereoselective Birch reduction alkylation of anisole with a chiral benzamide except that the pyrroloimidazolone replaces the achiral methoxy group and serves as the stereodetermining element. In addition, the synthesis and evaluation of the N–phenyl iridium complex derived from the annulated aminal with syn–stereochemistry in the backbone was achieved. Exposure of the neutral Ir–complexes to anionic nucleophiles such as MeLi resulted in an increase of electron density at the Ir atom that initiated C–H bond activation. Lastly, a N–heterocyclic carbene ligand derived from the N–benzyl analogue of the auxiliary was also investigated. Attempts to design a monodentate ligand as well as a bidentate ligand bearing an alcohol side chain were both shown to be unsuccessful at this time.