Electron-rich groups

Qiu et al. [11] reported that the aromatic tertiary amine with an electron-rich group on the N atom would favor nucleophilic displacement and thus increase the rate of decomposition of diacyl peroxide with the result of increasing the rate of polymerization (Table 1). They also pointed out that in the MMA polymerization using organic peroxide initiator alone the order of the rate of polymerization Rp is as follows ... 

This technique has also been applied in the synthesis of carbostyril analogues 15 and as in the previous example also this reaction is favored by an electron-rich group in the aniline-ring and an electron-poor group attached to the electrophihc specie (b. Scheme 6) [55]. The use of microwave irradiation can reduce the reaction times from 18-58 h to 80 min and the products are generally isolated in high yields and purities. 

The tendency of organotin compounds to form complexes with various organic compounds bearing electron-rich groups has been corroborated experimentally 6-16). 

The quantum yield of flavin fluorescence in proteins is very low in many cases, and the lifetimes are on the order of picoseconds. This is a result of the high electrophilicity of oxidized flavins, and their ability to quench fluorescence following electron transfer from the electron-rich groups of... 

The assistance of some electron-rich groups [94-96], heteroatoms [90, 97, 98] or filled cr-orbitals [99,100] in the oxidation of organic sulfides was studied in a series of papers (Scheme 24). Since the 3p orbitals of sulfur are quite compact compared to those of Se, the mentioned electronic and stereoelectronic effects are rather remarkable. These interactions (discussed in terms of a trans-annular... 

Nucleophilic group. An electron-rich group that tends to attack an electron-deficient nucleus. 

Compounds representing a non reversible mode of action. Electrophilic interactions involve substitution or conjugation of electron-rich groups to nucleophilic sites in cellular macromolecules. Volume 1(8). 

During arylations of carbon nucleophiles with aryl halides in the presence of palladium triarylphosphine complexes products containing the aryl group of the phosphine can result (Scheme8.16). These reactions proceed via reversible arylation of the Pd-bound phosphine, which occurs at temperatures above 50 °C, particularly readily in the presence of iodide [11] (see Section 8.2). Electron-deficient aryl groups usually migrate less readily than electron-rich groups [23, 25],... 

Ritter9,17 has expressed the view that the reactions involve the formation of a carbonium ion from the alcohol or alkene which subsequently A-alkylates the nitrile. The intermediate product was thought to be the imidol hydrogen sulfate (25) from which the hydrogen sulfate residue is displaced nucleophilically by the electron-rich group Y. 

Syntheses Involving Reactions with Electron-Rich Groups... 

Participation of a neighbouring electron-rich group will occur more significantly for a developing secondary carbocation centre than a tertiary one. The solvolysis of l-arylhexen-5-yl chloride [16] proceeds via ordinary... 

Note The [M/TIME)JX complexes were used to determine the nature of the M-carbene bond. The bond was found to be stabilised by considerable n interactions between the electron-rich group 11 metals and the carbene p-ti orbitals. 

For the formation of thiiranes from alkenes, it seems best to use the arenethiosulfenyl chloride method since this appears to result in the highest yields. While the sulfur monochloride method can be used, the yields are ically poor to moderate over a wide range of substrates. For both methods there are some common problems which include competing group reactivity (other alkenes or electron-rich groups) and, of course, the stench associated with many sulfides. 

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