What is umpolung reactivity?
What is Umpolung? Any process by which the normal alternating donor and acceptor reactivity pattern of a chain, which is due to the presence of O or N heteroatoms, is interchanged. Reactivity umpolung is most often achieved by temporary exchange of heteroatoms (N, O) by others, such as P, S, and Se.
What is umpolung give an example?
Carbonyl umpolung / anion relay chemistry Dithiane chemistry is a classic example of polarity inversion. This can be observed in the Corey-Seebach reaction. Ordinarily the oxygen atom in the carbonyl group is more electronegative than the carbon atom and therefore the carbonyl group reacts as an electrophile at carbon.
What is the meaning of synthons?
synthon (plural synthons) (chemistry) In retrosynthetic analysis, a structural unit within a molecule which is related to a possible synthetic operation.
What is Retrosynthesis in organic chemistry?
Retrosynthesis is a method of chemical synthesis which involves “deconstructing” a target molecule into its readily available, simple starting materials in order to assess the best synthetic route.
What do you mean by Ylide?
An ylide is defined as a neutral dipolar molecule containing a negatively charged atom directly attached to a positively charged heteroatom, in which the negatively charged atom is a nucleophilic center and the onium group is usually a good leaving group.
What is Chemoselectivity in organic chemistry?
IUPAC defines chemoselectivity as “the preferential reaction of a chemical reagent with one of two or more different functional groups,” a definition which describes in rather understated terms the single greatest obstacle to complex molecule synthesis.
What is FGA in retrosynthesis?
An example of Functional Group Addition (FGA) (iii) Functional Group Removal: FGR. This transformation involves the removal of a particular functional group during the retrosynthesis.
What is retrosynthesis used for?
Retrosynthesis is well suited for discovering different synthetic routes and comparing them in a logical and straightforward fashion. A database may be consulted at each stage of the analysis, to determine whether a component already exists in the literature.
What is ylide in organic chemistry?
What is phosphonium ylide?
Phosphonium (P)-ylides—where the cationic site is composed of a phosphonium ion and the negatively charged atom directly attached to the phosphorus center—are a specific type of zwitterion, and they are commonly used or invoked as a key intermediate in the Wittig reaction.