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Showing 1 to 20 of 108 for “"Benzylic"”.
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Asymmetric synthesis of benzylic and heterobenzylic amines
C2-Symmetrical, enantiopure 2,6-di[1-(1-aziridinyl)alkyl]pyridines (DIAZAPs) were prepared by a high-yielding, three-step sequence starting from 2,6-pyridinedicarbaldehyde and (S)-valinol or (S)-phenylglycinol. The new compounds were tested as ligands in palladium-catalyzed allylation of carbanions …
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Manganese-catalyzed intermolecular benzylic C–H amination
… for a highly site-selective intermolecular benzylic C—H amination of bioactive molecules and natural products. [Mn(ClPc)] is selective for benzylic C—H bonds over other C—H bond types and selects among multiple benzylic C—H bonds based on their electronic and steric properties.
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Applying Trichloroacetimidates to the Synthesis of Benzylic Trichloroacetamides & Functionalized Indoles
… a similar reaction, the rearrangement of benzylic trichloroacetimidates to access benzylic trichloroacetamides. The benzylic rearrangement was shown to proceed under two different sets of conditions: thermal and Lewis-acid catalyzed (TMSOTf). The corresponding secondary benzylic …
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Asymmetric Syntheses With (-)-Sparteine-Complexed Benzylic and Allylic Organolithium Reagents
The kinetic resolution of racemic cyclic unsaturated esters with the organolithium intermediates derived from lithiation of N-Boc- N-(p-methoxyphenyl)cinnamylamine with n -BuLi/(-)-sparteine was investigated. Kinetic resolution in conjugate addition reactions with alpha,beta-unsaturated lactones …
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Computational Studies of Protonated Cyclic Ethers and Benzylic Organolithium Compounds
Protonated epoxides feature prominently in organic chemistry as reactive intermediates. Gas-phase calculations studying the structure and ring-opening energetics of protonated ethylene oxide, propylene oxide and 2-methyl-1,2-epoxypropane were performed at the B3LYP and MP2 levels (both with the …
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Mechanistic studies of asymmetric induction at benzylic centers of organolithium species
The mechanisms of asymmetric induction involving the lithiation and substitution of N-benzyl-N-Boc-N-p-methodically amine and N-benzyl-N-Boc-N-3-chloropropyl amine were investigated and are reported here. These two substrates undergo deprotonation with butyllithium in the presence of the chiral …
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A dimensional analysis of the benzylic hydroxylase active site in mortierella isabellina
The spatial limits of the active site in the benzylic hydroxylase enzyme of the fungus Mortierella isabellina were investigated. Several molecular probes were used in incubation experiments to determine the acceptability of each compound by this enzyme. The yields of benzylic alcohols provided …
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Computational and Spectroscopic Determination of Lithiated Benzylic Nitriles in THF/HMPA Solution
… determination—particularly for lithiated benzylic nitriles in low dielectric, ethereal media. Chapter 1 of this dissertation presents a review of the synthetic utility of metalated nitriles and the spectroscopic and computational techniques employed to characterize their solution …
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STEREOSPECIFIC SUZUKI-MIYAURA CROSS-COUPLING OF CHIRAL BENZYLIC BORONIC ESTERS AND VINYL BROMIDES
The Suzuki-Miyaura cross-coupling reaction is a powerful method for the construction of carbon-carbon bonds in academia and industry. Despite extensive research in this area and the significance of the reaction, it is most often employed to prepare flat, Csp2-Csp2 bonds between two aryl groups. …
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Asymmetric Lithiation-Substitution Sequences of Functionalized Allylic and Benzylic Amines Mediated by (-)-Sparteine
Modification of the allyl amine with selected substituents at the beta and gamma-positions allowed for an examination of yields, product distributions, enantioenrichments, mechanistic understanding and synthetic applications. With an extended allyl amine, enantioenriched diene products were …
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Cascade Annulation and Ring-Opening Reactions of Castagnoli-Cushman-Derived Allylic and Benzylic Thiomorpholinonates
<p>Sulfur-containing compounds are prevalent in antibiotics, essential amino acids, bacterial RNA, food flavors, and enzymes. The divalent sulfur atom introduces a metabolic liability from a drug discovery standpoint. Indeed, it is quite telling that all the top ten best-selling drugs in 2012 …
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Mechanistic Investigations and Synthetic Development of (-)-Sparteine Mediated Asymmetric Benzylic Lithiation-Substitution Reactions of Secondary Amides
The synthetic utility of the lithiation-substitutions of N-(2-phenethyl)isobutyramide has also been investigated. Enantioenriched substituted products have been carried forward in the synthesis of 1,4-disubstituted dihydro- and tetrahydroisoquinolines. Variation of either substituent is convenient …
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Intermolecular and intramolecular asymmetric induction at the beta-benzylic position of carboxamides in directed lithiation-substitution sequences
Asymmetric induction at the $\beta$-benzylic position of secondary carboxamides in directed lithiation-substitution reactions has been achieved intermolecularly by using ($-$)-sparteine as the external chiral ligand and intramolecularly by using $\alpha$-methylbenzylamine as the covalently attached …
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Studies of alpha-lithioamine synthetic equivalents: I. Elaboration of primary amines. II. Detection of an intermediate in the lithiation of a benzylic urea
Reagents for the $\alpha$-substitution of N-Boc-benzylamine and N-Boc-allylamine have been developed via dilithiation and electrophilic substitution. Discussion of the specific conditions employed to accomplish these transformations is presented, as well as mechanistic speculation. Dilithiation and …
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(--)-Sparteine Mediated Asymmetric Synthesis Through Conjugate Addition of Allylic and Benzylic Organolithium Species: Development of a Methodology and Its Application Toward a Total Synthesis
The synthetic utility of the methodology is demonstrated with the synthesis of diastereo-, and enantiomerically pure 2,3,4-trisubstituted gamma-lactams in high yield. In addition, conjugate addition of the allylic organolithium species with N-protected 4-pyridones provides high yields of the …
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Novel applications of a 4-DMAP-derived organic electron donor under photoactivation
… metal-free reductive C-O bond fragmentations of benzylic esters and ethers with photoactivated donor 1. Benzylic esters e.g. 8 were reduced to acids e.g. 10 via SET process and the complete absence of isolated toluenes e.g. 9 was attributed to trapping of benzyl radical intermediates with the …
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Mechanistic Studies of Vitamin B(12)-Catalyzed Dechlorination and Carbon-Carbon Bond-Forming Reactions
… forming a new carbon-carbon bond between the benzylic carbons of each coupling partner. Dimerization products were obtained in good to excellent yields for mono- and 1,1-disubstituted alkenes, and dienes containing one aryl alkene underwent intramolecular cyclization in good yields. …
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Exploration of Carbon-oxygen and Carbon-nitrogen Bond Formation Utilizing Trichloroacetimidates and Investigations of New Reactions Mediated By Oxoammonium Salts
… esters without electron donating groups on the benzylic ring. The trichloroacetimidates therefore provide inexpensive and convenient methods that should find use in the formation of esters in complex substrates. Benzylic amines are important structural features in pharmaceuticals, food …
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TRANSITION METAL CATALYZED CROSS-COUPLINGS OF ALKYL SULFONE ELECTROPHILES
… cross-coupling of π-extended tertiary benzylic and allylic sulfones with arylboroxines. A variety of tertiary sulfones were reacted to afford quaternary products in good yields and we identified a unique phosphine ligand capable of promoting the challenging cross-coupling reaction. The …
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