1,721,336 research outputs found
Comparing and Taming the Reactivity of Lithiated Oxetanes and Tetrahydrofurans: Concepts and Applications
No full textAmong saturated oxygen heterocycles, both oxetane and tetrahydrofuran derivatives are important scaffolds in a broad array of biologically active natural compounds (1). However, while increasing attention has recently been paid to the regio- and stereoselective construction of these ring motifs and new reactivity discover, direct functionalization processes remain extremely rare (2). In addition, conventional strong organolithium bases are long-lasting known to promote, in the case of oxetanes, both nucleophilic substitution reactions at C-2 in competition with alpha-lithiation, and reverse [3+2] cycloadditions for tetrahydrofurans. The occurrence of such competing reaction pathways and fragmentation reactions has most likely discouraged the use of these heterocycles as starting materials in organic synthesis for many years. In this communication, we report and compare the protocols found for a direct regioselective lithiation-electrophile interception of both aryloxetanes (3) and aryltetrahydrofurans. The role played by aggregation, the nature of the solvent, and the presence of co-solvents in coaxing alpha-lithiated intermediates to react as nucleophiles (thereby suppressing their intrinsic carbene-like character) while keeping their cycloanionic structure intact, will be discussed. The ability to effect ortho metallation reactions together with mechanistic, stereochemical aspects, and synthetic applications will be tackled as well
Stories on Lithiation of Small Heterocycles: Rich Synergy among Synthetic, Mechanistic, and Structural Investigation; "Anorganisch-Chemisches Kolloquium", Georg-August Universität, Institut für Anorganische Chemie, Göttingen (Germany), January 22, 2013
No full textThe Beauty of Reactive Intermediates. Aziridinyl- and Oxiranyllithiums: Structure, Dynamics and Reactivity – Cerimonia di Conferimento del Sigillo d’Oro dell’Università di Bari al Prof. Jean-Marie Pierre Lehn, Bari, 23 settembre 2008
No full textThe Quest for New Chiral and Configurationally Stable Lithium Carbenoids for Asymmetric Synthesis
No full textCarbenes and Carbenoids: From Simple Laboratory Curiosities to Valuable Reagents for Organic Synthesis, XXXVII “A. Corbella” Summer School on Organic Synthesis
No full textChallenges and Opportunities in Lithium Chemistry: From Applications in Medicine to Stereoselective Syntheses through Kinetic and Mechanistic Investigations – Faculty of Chemistry and Pharmacy, Ludwig-Maximilians Universität (LMU), Munich (Germany), February 7, 2011
No full textIl Litio all’Interfaccia tra Scienza, Medicina e Tecnologia – Giornata Pugliese su Farmaco e Prodotti per la Salute (I edizione), Bari, 28 Gennaio 2010
No full textStabilized α-Lithiated Oxiranes: Synthetic and Mechanistic Aspects, Goteborg University, May 26, 2003
No full textFinding Joy with Lithium Chemistry: From Application in Medicine to Stereoselective Synthesis Through Tailored Self-Assembly
No full text- …
