umpolung造句

• The thioacetals are useful in " umpolung " of carbonyl groups.
• It is therefore important to understand and develop methods to induce umpolung in organic reactions.
• Mercuric chloride is used to remove dithiane groups attached to a carbonyl in an umpolung reaction.
• The human body can employ cyanide-like umpolung reactivity without having to rely on the toxic cyanide ion.
• The thiazolium ring in TPP is deprotonated within the hydrophobic core of the enzyme, resulting in a carbene which is capable of umpolung.
• Unlike the Staudinger ?-lactam synthesis, the Umpolung ketene in the Lectka ?-lactam synthesis behaves as the nucleophile rather than the electrophile.
• For example, an acyl anions are not stable species, but the acyl anion synthon can be used to represent reagents such as lithiated dithianes, which are nucleophilic and often used in umpolung chemistry
• N heterocyclic carbenes ( NHCs ) are an emerging class of organocatalysts that are able to induce Umpolung reactivity as well as normal polarity transformations, however until recently these have not been broadly used in total synthesis due to limited substrate scope.