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New perspectives and applications in organolithium chemistry: halocarbenoids and reductive lithiation

Mamuye, Ashenafi Damtew (2015) New perspectives and applications in organolithium chemistry: halocarbenoids and reductive lithiation. Doctoral Thesis.

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We report on the employment of 2-methyltetrahydrofuran and cyclopentyl methyl ether as alternative green solvents for the efficient generation of radical anions of Polycyclic Aromatic Hydrocarbons and their employment in the generation of organolithium reagents. 2-MeTHF was successfully employed as a solvent in the reductive lithiation of the benzylic C–O bond of phthalan, of the aromatic C–Cl bond of 4-chlorobenzyl methyl ether, and of the C–N bond of N-phenylaziridine. Results obtained with N-phenylaziridine show that such a PAH mediated reductive lithiation of is strongly dependant on the solvent employed.
We next investigated the reactivity of Weinreb amides with cyanomethyllithiums to access β-oxonitriles. Such a transformation occurs in the presence of primary, secondary and tertiary nitrile-containing carbanions. The study of the previously undisclosed 15N- and 17O-NMR data was correlated with analogous substrates thus, highlighting the spectroscopic effect of the β-oxonitrile group. Subsequently, the homologation of isocyanates with lithium carbenoids to reach α-halo or α,α-dihaloamides was realized: the protocol is high-yielding and no lose of optical purity was noticed in the presence of chiral materials. Finally, we studied the homologation of isatins derivatives with lithium carbenoids to access spiro-epoxyoxindoles.

Item Type:Doctoral Thesis
ID Code:10536
Contributors:Azzena, Ugo and Pace, Vittorio
Publisher:Università degli studi di Sassari
Uncontrolled Keywords:Reductive lithiation, green solvents, 2-methyltetrahydrofuran, cyclopentyl methyl ether, halocarbenoids, cyanomethyllithiums, homologation
Subjects:Area 03 - Scienze chimiche > CHIM/06 Chimica organica
Divisions:001 Università di Sassari > 01-a Nuovi Dipartimenti dal 2012 > Chimica e Farmacia
Cicli, scuole e corsi:Ciclo 27 > Scienze e Tecnologie chimiche > Scienze chimiche
Deposited On:18 Mar 2015 10:15

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