Chemical process intended to reverse the polarity of a molecular functional group
In organic chemistry, umpolung (German:[ˈʔʊmˌpoːlʊŋ]) or polarity inversion is the chemical modification of a functional group with the aim of the reversal of polarity of that group.[1][2] This modification allows secondary reactions of this functional group that would otherwise not be possible.[3] The concept was introduced by D. Seebach (hence the German word umpolung for reversed polarity) and E.J. Corey. Polarity analysis during retrosynthetic analysis tells a chemist when umpolung tactics are required to synthesize a target molecule.
^Seebach, D. (1979). "Methods of Reactivity Umpolung". Angewandte Chemie International Edition in English. 18 (4): 239–258. doi:10.1002/anie.197902393.
^Gröbel, B. T.; Seebach, D. (1977). "Umpolung of the Reactivity of Carbonyl Compounds Through Sulfur-Containing Reagents". Synthesis. 1977 (6): 357. doi:10.1055/s-1977-24412. S2CID 95705677.
^Seebach, D.; Corey, E. J. (1975). "Generation and synthetic applications of 2-lithio-1,3-dithianes". The Journal of Organic Chemistry. 40 (2): 231. doi:10.1021/jo00890a018.
In organic chemistry, umpolung (German: [ˈʔʊmˌpoːlʊŋ]) or polarity inversion is the chemical modification of a functional group with the aim of the reversal...
forget about their language and their origin. As a neologism, it echoes Umpolung, 'polarity inversion', leading to an interpretation akin to "ethnicity...
Boluda CJ, Juncá C, Soto E, de la Cruz D, Peña A (13 December 2019). "Umpolung in reactions catalyzed by thiamine pyrophosphate dependent enzymes". Ciencia...
inversion of polarity between R'(H)Cδ+=Oδ− and R'CLi(SR)2 is referred to as umpolung. The reaction is commonly performed using the 1,3-dithiane. The lithiated...
chemistry since the 1980s. They are related to enolates, but represent an umpolung of their reactivity. Homoenolates can be formed with a variety of different...
triazolium salts to be effective. The Stetter reaction is an example of umpolung chemistry, as the inherent polarity of the aldehyde is reversed by the...
of Hg(II) for thiolates. 1,3-Dithianes are more importantly employed in umpolung reactions, such as the Corey–Seebach reaction: 1,4-Dithiane is an organosulfur...
produce an acyl anion equivalent (see cyanohydrin or aldehyde-dithiane umpolung chemistry, as well as benzoin condensation). This anion attacks S1 of an...
They represent a subclass of sulfides. The thioacetals are useful in "umpolung" of carbonyl groups. Thioacetals and thioketals can also be used to protect...
chemistry and on the synthesis of beta-peptides. The development of the umpolung, a polarity inversion of the carbonyl group, with 1,3-propanedithiol together...
diazaphospholenes (scheme 3), the polarity of the P-H bond can be inverted (see: umpolung) and the resulting phosphine hydride can reduce a carbonyl group as in...
reactivity in displacement and addition reactions. Dithianation introduced umpolung chemistry, now a key concept in organic synthesis. The formations of dithianes...
resulting anion can be C-alkylated. The process is the foundation of the umpolung phenomenon. Like 1,2-ethanedithiol, propanedithiol forms complexes with...
S.; Yatham V. R.; Neudörfl J.-M.; Schlörer N. E.; Teles J. H. (2012). "Umpolung by N-Heterocyclic Carbenes: Generation and Reactivity of the Elusive 2...
Taylor, Carol M. (2006-08-01). "β-Glycosides of Hydroxyproline via an Umpolung Approach". Organic Letters. 8 (18): 3959–3962. doi:10.1021/ol061424m. ISSN 1523-7060...
(NHCs) are an emerging class of organocatalysts that are able to induce Umpolung reactivity as well as normal polarity transformations, however until recently...
W.; Shevchenko, Nikolay; Alabugin, Igor V. (2013). ""Stereoelectronic Umpolung": Converting a p-Donor into a σ-Acceptor via Electron Injection and a Conformational...
intermediates may also intercept nucleophiles in a process that involves umpolung at the α carbon. In addition, because reduction of monohalo ketones produces...
doi:10.1038/nchem.1607. Xavier Bugaut, Frank Glorius: Organocatalytic umpolung: N-heterocyclic carbenes and beyond. In: Chemical Society Reviews. 41,...
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