Related reagents reaction with nucleophiles

Quinoxalines undergo facile addition reactions with nucleophilic reagents. The reaction of quinoxaline with allylmagnesium bromide gives, after hydrolysis of the initial adduct, 86% of 2,3-diallyl-l,2,3,4-tetrahydroquinoxaline. Quinoxaline is more reactive to this nucleophile than related aza-heterocyclic compounds, and the observed order of reactivity is pyridine < quinoline isoquinoline < phenan-thridine acridine < quinoxaline. ... 

Nucleophilic Attack at Halogen.- Further applications of tertiary phosphine-tetrahalogenomethane and related "reagents" have been described. The reactions of primary and secondary alcohols with potassium carboxylates in the presence of the triphenylphosphine-tetrachloromethane reagent lead to the formation of esters in good yield. However, application of this procedure... 

Nitrones have a more reactive C=N bond toward nucleophilic addition compared to imines. In spite of this fact, there have been only a limited number of studies on the nucleophilic addition reactions of nitrones, particularly organometallic reagents.352-355 During the last decade, research related to reactions of nitrones with zinc-containing reagents was essentially focused on (i) dialkylzinc-assisted alkynylations356-358 and vinylations359 of nitrones, (ii) catalytic asymmetric nucleophilic additions to the C=N bond,360-364 and (iii) nitrone allylations by allylzinc halides.365,366... 

Closely related with the synthesis of ylides from carbenes is the use of ylides as carbene transfer reagents (CTR), that is processes in which the ylide is cleaved homolytically, liberating the nucleophile and the carbene, which could remain both coordinated to the metal or not (Scheme 10). Diphosphirane (34) can be obtained from the diphosphene by reaction with sulfur ylide Me2S(0)=CH2, which behave as a carrier of the CH2 unit [95]. Recent work of Milstein et al. shows that sulfur ylides decompose in the presence of Rh derivatives with vacant coordination sites affording Rh(l)-carbene complexes [96, 97]. Complexes (35-37) can be obtained from... 

While providing structural details and rates of intramolecular rearrangements-fragmentations, stable ion studies do not address questions relating to the reactivity of a carbocation with a second reagent, either with a solvent such as water or with some added nucleophile (Nu). Shown in Scheme 1.4 is the kinetic scheme for a limiting SnI solvolysis, that is, for a solvolysis that proceeds by way of a free carbocation. As is true for any reaction in which a reactive intermediate is formed as a stationary-state species, studies of this system cannot provide absolute rate con-... 

An important feature of many elimination reactions is that they occur with the same combinations of reagents that cause nucleophilic substitution. In fact, elimination and substitution often are competitive reactions. Therefore it should be no surprise that substitution and elimination have closely related mechanisms. 

The course of the reaction of the poly-O-acylglycosyl halides with nucleophilic reagents has recently received attention. Thus, Lemieux has related the theories of the mechanism of replacement reactions to some reactions in carbohydrate chemistry, and has summarized our knowledge concerning the mechanism of reaction of the poly-O-acylglycosyl halides. Hence, only those aspects of the subject which have become clarified by recent work need be discussed here. 

The reaction of LVII" and some related heterocycles with a large number of nucleophiles has been investigated thoroughly. Among the nucleophiles, which with few exceptions form sulfonium salts by their reaction with LVII", are water [194, 195], carboxylate ions [196, 197], pyridine [198], organometallic compounds like dialkylmercury and dialkylzinc [199], and Grignard reagents [200], alkenes and alkynes [201], and various aromatic compounds [202-204]. 

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