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Showing 1 to 20 of 46 for “"Acetals"”.
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Aromatic acetals : their synthesis and alkylation
… was to study the known methods of forming acetals and find one or several that could be used in further investigation. In connection with the reactions, the use of various catalysts was pertinent. Some of the catalysts used were hydrogen chloride, calcium chloride, ferric chloride, aromatic …
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Brønsted acid-catalyzed reaction of alkynyltrifluoroborates with acetals and ketals
… carbon-carbon bond forming methodology between acetals, ketals, and potassium phenylacetylene trifluoroborate salts. Excellent functional group tolerance is observed with this protocol including, halogen, nitrile, nitro, acid and carbonyl functionalities.
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Cycloadditions of ketene acetals with conjugated carbonyl compounds and chemistry of the resulting products
Contains fulltext : mmubn000001_027259145.pdf (Publisher’s version ) (Open Access)
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Lewis Base Activation of Lewis Acids in Asymmetric Aldol Reactions of Silyl Ketene Acetals
… 4 promoted aldol reaction of silyl ketene acetals and silyl dienol ethers with aldehydes. The weakly acidic species, silicon tetrachloride (SiCl 4), is activated by binding of a strongly Lewis basic chiral phosphoramide, leading to in situ formation of a chiral silyl cation. This species …
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Modifications to the Suzuki reaction and mechanistic insights on the NBS mediated cleavage of benzylidene acetals /
… initiated oxidative fragmentation of benzylidene acetals was investigated through the use of several test-case substrates in order to unravel the possible mechanistic pathways. This was performed by reacting the different acetals with N-bromosuccinimide and benzoyl peroxide in chlorobenzene at …
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Trifluoroethyl enol ethers, dienol ethers, and acetals: an investigation of their preparations, reactivities, and synthetic applications
The major portion of this work details our investigation of trifluoroethoxy (TFE) substituted compounds with particular emphasis given to their preparation and possible applications. The three types of compounds studied were trifluoroethoxy substituted ketals, enol ethers, and dienol ethers. The …
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Studies in Asymmetric Catalysis: Lewis Base Catalyzed, Enantioselective Addition of Trimethylsilyl Cyanide, Trimethylsilyltrifluoromethane, and Glycolate-Derived Silyl Ketene Acetals to Aldehydes
… the addition of glycolate-derived silyl ketene acetals to aldehydes. The sense of diastereoselectivty could be modulated by changing the size of the substituents on the silyl ketene acetals. In general, the trimethylsilyl ketene acetals derived from methyl glycolates with a large protecting …
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TEMPLATE DIRECTED C-H INSERTION REACTIONS FOR STEREOCONTROLLED SYNTHESIS OF HETEROCYCLES
… an aldol type condensation between the aldehyde acetals and ethyldiazoacetate. Good yields of the diazoketols and the required diazoacetoacetates were isolated. Importantly, the sequence led to the development of a general and efficient one-pot protocol for the synthesis of diazoacetoacetate …
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Radical additions of hydrocarbons, ethers and acetals to alkenes via allyl transfer reaction: A new chain reaction for C-H bond functionalization
… useful for the functionalization of ethers and acetals. The functionalization of various cyclic and acyclic ethers was performed using these allyl transfer reactions. This reaction was also performed in-solution, which allowed us to perform these reactions at low reagent concentrations. Kinetic …
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Part I. Stereochemical Studies on the Addition of Allylsilanes to Aldehydes. Part II. Stereochemical Studies on the Addition of Allylmetal Reagents to Acetals
Systematic investigations have been performed to determine the mechanism and origin of selectivity of the allylmetal-aldehyde reaction. Initial studies were performed to determine the solution structure of Lewis acid-aldehyde complexes. The intramolecular allylmetal-aldehyde reaction was next …
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(Trimethylsilyloxy)acrylsäureester in der organischen Synthese
… reacted with different electrophiles such as acetals, thioacetals and mixed N,O-acetals to gain access to densly functionalized gamma-substituted alpha-keto esters. Simple metal triflates such as copper(II)triflate was used as catalyst. The thus obtained products could easily be transformed …
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Stabilization of transition states of organic reactions by cyclodextrins, micelles, and dendrimers
… of SDS catalyze the hydrolysis of aromatic acetals and orthoesters in the acidic solution. There is no sharp linear correlation between the substrate and the transition state binding for different acetals and orthoesters, which reflects the importance of both nature of the substituent, and …
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Enantioselective synthesis using bromoacetals.
… enriched dimethyl tartrate (S)-bromoalkyl aryl acetals is described. An investigation into the effects of solvent, source of anhydrous acid, workup procedure, source of bromine and temperature upon the bromination of these dimethyl tartrate acetals is discussed. Direct conversion of these …
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Studies in Furobenzopyran Chemistry
… to give the corresponding 3-acyl(thio)chromone acetals. A new rearrangement accompanies the formation of acetals from 3-acetyl- or 3-benzoyl- chromone giving a 2-methyl- or 2-phenyl- 3-formylchromone acetal. The rearrangement is initiated by conjugate addition of the diol to the chromone ring. …
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New methodology for the organocatalysed α-Amination reaction
… 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 …
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Electrochemically-Enabled Late-Stage Peptide C-terminal Modifications
… leveraging electrochemically-generated N,O-acetals as valuable handles for divergent late-stage modifications. Chapter One introduces C-terminally modified peptides as promising biochemical targets and highlights recent advances in C-terminal peptide modification, especially decarboxylation …
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Electrochemically-Enabled Late-Stage Peptide C-terminal Modifications
… leveraging electrochemically-generated N,O-acetals as valuable handles for divergent late-stage modifications. Chapter One introduces C-terminally modified peptides as promising biochemical targets and highlights recent advances in C-terminal peptide modification, especially decarboxylation …
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Tandem Double Intramolecular [4+2]/[3+2] Cycloaddition of Nitro Olefins: Part I: Construction of Piperidine Rings. Part II: Construction of Vicinal Quaternary Stereogenic Centers. Part III: Progress Toward a Total Synthesis of Daphnilactone B
… to provide a mixture of two epimeric nitroso acetals. Ozonolysis of the cycloadducts, followed by hydrogenolysis and intramolecular acylation provided the intermediates for the total synthesis that may be elaborated to daphnilactone B. Possible routes to complete the synthesis are also …
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Asymmetrische Synthese funktionalisierter Homoallyl- und Homopropargylalkohole mittels der Sulfoximin-Route
… cyclisation of the chiral allylic silanes with acetals yielded optically pure tetrasubstituted tetrahydrofurans.
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