Global ETD Search

1	Purification of Ethyl Diazoacetate by Vacuum Distillation for use in Cyclopropanation Reactions Olukanni, Ayobami, Eagle, Cassandra T, Adesina, olumide, Mohseni, Reza M. 12 April 2019 (has links) Environmentally friendly insecticides have long been desired in the production of food. Pyrethiod compounds not only decompose under light and heat, but they are highly toxic to insects while having effectively no toxicity to mammals. The cis-cyclopropane ring in pyrethiod insecticides is the most challenging component to synthesize. We are exploring the best parameters for the most effective cis-Cyclopropanation reactions. An alkene and a diazo compound react together in the presence of a dirhodium catalyst to produce cyclopropanes. First however, the starting materials must be pure. My part of the project is to purify ethyl diazoacetate(EDA). Column chromatography has been used, but yielded no fraction containing EDA as determined by Gas chromatography/Mass spectrometry. Extraction of EDA with sodium carbonate solution yielded similar results. Thus, I turned to distillation at reduced pressure. This method produced EDA in high enough purity to be used in cyclopropanation reactions. The purity of EDA was determined by H-1 nuclear magnetic resonance spectroscopy. Ethyl diazoacetate Catalyst Cyclopropanation Chemicals and Chemical Properties
2	Metal Carbenoid Ring Opening of 2-alkyl and Alkoxy Furan-Synthesis, Application and SAR of 1,6-Dioxo-2,4-diene Derivatives Shieh, Po-Chuen 29 June 2001 (has links) Abstract 2-Methoxy- and 2-trimethylsilyloxyfuran undergo facile ring opening reaction upon treatment with metal carbeniod. Treatment of 2-methoxy-furan with ethyl diazoacetate and aryl-£\-diazocarbonyl compounds under metal catalysis afford (Z,E)-2,4-hexadienedioate and aryl-6-oxo-2,4-hexadienoates respectively. When 2- trimethylsilyloxyfuran was used, desilylation occurred to give directly the monoprotected (Z,E)-muconic acid and 6-aryl-6-oxo-2,4-hexadienoic acids. We have synthesized aromatic dienyl diketone using the method of Wenkert from aromatic diazo ketone and 2-methylfuran. This method was found to give a mixture of (Z,E)/(E,E)-dienyl diketones. The anticancer, antibacterial and vasorelaxing activities are evaluated. All the aromatic dienyl diketones synthesized exhibit strong in vitro inhibition of tumor cell and micro0organisms growth respectively, and three of these compounds exhibit strong vasorelaxing effect. Reaction of 1,6-dioxo-2,4-diene with P2S5 and Lawesson¡¦s reagent affords the 2,5-disubstituted thiophene. This reaction can take place regioselectively in the presence of BF3-etherate catalysis, useful for the synthesis of arylthiophene. We have demonstrated a new methodology for the facile synthesis of arylthiophene. Lawesson¡¦s reagent 2-methoxy-furan 2-trimethylsilyloxyfuran ethyl diazoacetate P2S5 aryl-£\-diazocarbonyl compounds
3	Investigations into cyclopropanation and ethylene polymerization via salicylaldiminato copper (II) complexes Boyd, Ramon Cornell 23 January 2007 Two distinct overall research objectives are in this Masters thesis. Very little relates the two chapters apart from the ligands. The first chapter addresses diastereoselective homogeneous copper catalyzed cyclopropanation reactions. Cyclopropanation of styrene and ethyl diazoacetate (EDA) is a standard test reaction for homogeneous catalysts. Sterically bulky salicylaldimine (SAL) ligands should select for the ethyl trans-2-phenylcyclopropanecarboxylate diastereomer. Steric bulk poorly influences trans:cis ratios. Salicylaldiminine ligands do not posses the correct symmetry to affect diastereoselectivity. The SAL ligand belongs to the Cs point group in the solid state. Other ligand motifs are more effective at altering the trans:cis ratios. The second chapter addresses the general route toward successful copper(II) ethylene polymerization catalysts. Catalytic activity of the copper(II) complexes is very low. Polymer chain growth from a copper catalyst is very unlikely. Copper-carbon bonds decompose by homolytic cleavage or C-H activation. Copper-alkyls and aryls readily decompose into brown colored oils and salts with different colors. Ligand transfer to trimethylaluminum (TMA) appears to explain low yield ethylene polymerization. bulky migratory insertion mechanism coordination/insertion methodology d-block metal late transition metal phenolic ring coordination number ketimine precatalysts ketimine nitrogen bis(salicylaldiminato)copper(II) ratio cyclopropane steric bulk salicylaldiminato TMA salt trimethylaluminum aryl oil alkyl copper-aryls copper-alkyls C-H activation homolytic homolytic cleavage copper(II) polymerization ethylene cis trans symmetry diastereomer salicylaldimine SAL EDA ethyl diazoacetate styrene cyclopropanation copper diastereoselective steric protection stable CH(SiMe3)2 intermediate catalytic activity associated TMA free TMA vacant coordination site hydrolysis Lewis acid halogen anionic anionic ligand donor ligand monodentate anionic ligand aluminum(III) monodentate polymer chain polymer chain aluminum-carbon bond bulky SAL ligand open coordination site first row transition metal PE paramagnetic high molecular weight polyethylene alkylate methylaluminoxane MAO anionic ligands arylate aluminum carbon aluminum carbon bond beta-hydrogen elimination beta hydrogen elimination Aufbau reaction Aufbau neutral dialkyl aluminum aluminum-alkyl aluminum alkyl copper(0)
4	Investigations into cyclopropanation and ethylene polymerization via salicylaldiminato copper (II) complexes Boyd, Ramon Cornell 23 January 2007 (has links) Two distinct overall research objectives are in this Masters thesis. Very little relates the two chapters apart from the ligands. The first chapter addresses diastereoselective homogeneous copper catalyzed cyclopropanation reactions. Cyclopropanation of styrene and ethyl diazoacetate (EDA) is a standard test reaction for homogeneous catalysts. Sterically bulky salicylaldimine (SAL) ligands should select for the ethyl trans-2-phenylcyclopropanecarboxylate diastereomer. Steric bulk poorly influences trans:cis ratios. Salicylaldiminine ligands do not posses the correct symmetry to affect diastereoselectivity. The SAL ligand belongs to the Cs point group in the solid state. Other ligand motifs are more effective at altering the trans:cis ratios. The second chapter addresses the general route toward successful copper(II) ethylene polymerization catalysts. Catalytic activity of the copper(II) complexes is very low. Polymer chain growth from a copper catalyst is very unlikely. Copper-carbon bonds decompose by homolytic cleavage or C-H activation. Copper-alkyls and aryls readily decompose into brown colored oils and salts with different colors. Ligand transfer to trimethylaluminum (TMA) appears to explain low yield ethylene polymerization. bulky migratory insertion mechanism coordination/insertion methodology d-block metal late transition metal phenolic ring coordination number ketimine precatalysts ketimine nitrogen bis(salicylaldiminato)copper(II) ratio cyclopropane steric bulk salicylaldiminato TMA salt trimethylaluminum aryl oil alkyl copper-aryls copper-alkyls C-H activation homolytic homolytic cleavage copper(II) polymerization ethylene cis trans symmetry diastereomer salicylaldimine SAL EDA ethyl diazoacetate styrene cyclopropanation copper diastereoselective steric protection stable CH(SiMe3)2 intermediate catalytic activity associated TMA free TMA vacant coordination site hydrolysis Lewis acid halogen anionic anionic ligand donor ligand monodentate anionic ligand aluminum(III) monodentate polymer chain polymer chain aluminum-carbon bond bulky SAL ligand open coordination site first row transition metal PE paramagnetic high molecular weight polyethylene alkylate methylaluminoxane MAO anionic ligands arylate aluminum carbon aluminum carbon bond beta-hydrogen elimination beta hydrogen elimination Aufbau reaction Aufbau neutral dialkyl aluminum aluminum-alkyl aluminum alkyl copper(0)

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