Nucleophile common types

A synthetically useful reaction known as the Michael reaction, or Michael addition, involves nucleophilic addition of carbanions to a p unsaturated ketones The most common types of carbanions used are enolate 10ns derived from p diketones These enolates are weak bases (Section 18 6) and react with a p unsaturated ketones by conjugate addition... 

The most common types of aryl halides m nucleophilic aromatic substitutions are those that bear o ox p nitro substituents Among other classes of reactive aryl halides a few merit special consideration One class includes highly fluormated aromatic compounds such as hexafluorobenzene which undergoes substitution of one of its fluorines on reac tion with nucleophiles such as sodium methoxide... 

A full description of how a reaction occurs is called its mechanism. There are two general kinds of mechanisms by which reactions take place radical mechanisms and polar mechanisms. Polar reactions, the more common type, occur because of an attractive interaction between a nucleophilic (electron-rich) site in one molecule and an electrophilic (electron-poor) site in another molecule. A bond is formed in a polar reaction when the nucleophile donates an electron pair to the electrophile. This movement of electrons is indicated by a curved arrow showing the direction of electron travel from the nucleophile to... 

As stated previously, the addition of nucleophiles to chiral carbonyl compounds is a very common type of reaction which produces diastereomeric mixtures. The diastereoselectivity varies with the reagents and conditions. Some examples are... 

Lactams can act as acylating agents to those nucleophiles that effect the cleavage of the (3-lactam Ni C2 bond. Indeed, irreversible acylation of an enzyme amino acid unit belonging to a bacterial cell is the most common type of molecular mechanism for the (3-lactam antibiotics mode of action. Similarly, the process is on grounds of... 

Nucleophiles are either negatively charged or neutral species with a pair of electrons in a high energy filled orbital that they can donate to electrophiles. The most common type of nucleophile has a nonbonding lone pair of electrons. Usually these are on a heteroatom such as O, N, S, or P. 

Conversion of a 1,2-diamine into a pyrazine ring is a common type of reaction (see Section 6.3.1.). In this dinucleophile -I- dielectrophile approach, heteroatoms function as nucleophiles and 1,2-dicarbonyl or related compounds, as the electrophilic component. The difference in relative reactivities at the termini of the individual components may influence the formation of a single product alternatively, the relative reactivities may be so similar that a mixture of isomers is formed. 

This commoner type of reaction involves the attack of carbon or heteroatom nucleophiles onto carbonyl compounds, by direct or conjugate addition, and onto imines. Because we have just dealt with boranes we shall start with the reaction of allylic boron compounds with such electrophiles. You might strictly not call this nucleophilic attack. 

The common types of chemical reactions found in living cells are nucleophilic substitution, elimination reactions, addition reactions, isomerization reactions, and oxidadon-reduction reacdons. 21. In addition to being an important energy source, carbohydrates are important structural molecules in organisms and have a role in intracellular and intercellular communication. 

We discerned three kinds of refunctionalization unit reactions which can usefully couple with a construction in a nonstop, or one-step, procedure prior reduction to carbanion nucleophiles, elimination following construction, or various tautomerizations before or after construction. The overall net structural changes for these composite constructions were then added to our list of construction half-reactions and, after some further subdivision of common types into chemically recognizable subheadings, we had expanded the list from the six of Figure 4 to 24 half-reactions ... 

Sj,jl a unimolecular nucleophilic substitution reaction one of the most common types of organic reactions seen in biochemistry, the rate of the reaction follom fii t-order kinetics (7.6)... 

The second set of examples involves the use of thionium ions as electrophiles in inter- and intramolecular processes to obtain a-substituted sulfides (see 24 25, Scheme 20.7T which is the most common type of Pummerer reaction. Applications of this classical Pummerer rearrangement are exemplified in the synthesis of trans-solamin, the synthesis of indolizidine alkaloids, and the synthesis of the CDE ring of erinacine E. The first exanple fScheme 20.10 uses Pummerer chemistry in the generation of a thionium ion, which reacts in an intermolecular tin-mediated ene reaction the second one fScheme 20.11 uses Pummerer chemistry to introduce a nitrogen-containing heterocycle by intramolecular addition to form the coniceine core and the third example fScheme 20.12 is an intramolecular silicon-induced Pummerer reaction with oxygenated nucleophiles applied to the synthesis of a precursor of erinacine. Details of these Pummerer-based strategies are discussed below. 

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