Grignard reagents, aryl hydrolysis

Grignard reagents (aryl, vinyl, or alkyl) can be electrograted by oxidation on Si-H to give 5f-alkyl, vinyl, or aryl mnltilayers through the formation of radicals [420-421]. The films are therefore quite similar to those obtained from diazonium salts. The drawback of the method lies in the necessity to work under oxygen- and water-free conditions to prevent the oxidation of Si and the hydrolysis of the reagent. 

Total basicity is measured by standard acid—base titration techniques. The activity divided by the total basicity should be greater than 90%. If it is not, then the Grignard reagent should be checked for unreacted alkyl or aryl haUde, homo-coupled product, hydrolysis products, and oxidation products. 

Organometallic compounds can be hydrolyzed by acid treatment. For active metals such as Mg, Li, and so on, water is sufficiently acidic. The most important example of this reaction is hydrolysis of Grignard reagents, but M may be many other metals or metalloids. Examples are SiRs, HgR, Na, and B(OH)2- Since aryl Grignard and aryllithium compounds are fairly easy to prepare, they are often used to prepare salts of weak acids, for example,... 

The addition of Grignard reagents to isocyanates gives, after hydrolysis, N-substituted amides. This is a very good reaction and can be used to prepare derivatives of alkyl and aryl halides. The reaction has also been performed with... 

While chlorosilanes are susceptible to hydrolysis, aryltrialkoxysilanes are not Treating the Grignard reagent generated from aryl bromide 127 with SiCL, then with a solution of pyridine in methanol furnished aryltrimethoxysilane 128 [104], Subsequent Pd-catalyzed coupling between 128 and 3-bromopyridine assembled biaryl 129 in 72% yield with the aid of TBAF. 

The classic caustic fusion of sulfonic acid salts has been used for preparing 2,6-dinaphthol and its derivatives. Other more recent procedures have employed the direct hydrolysis of aryl bromides and the oxidation of aryl Grignard reagents. ... 

Murdoch and coworkers carried out amination reactions of aryl Grignard reagents and aryllithiums with oximes using O-p-toluenesulfonyl tetraphenylcyclopentanone oxime (0-tosyltetracyclone oxime) 6g (Scheme 61). The imine is extracted with benzene, purified, and then converted to amine and oxime by reacting with excess hydroxylamine in aqueous pyridine at room temperature. Amines are obtained following acidic hydrolysis. 

Et2C6H3 ) is essentially planar. These tin-oxygen heterocycles are prepared by hydrolysis of the corresponding diorganotin dihalides, which, in the case of the aryl derivative, is formed by the reaction of (2,4-pentane-dionato)tin dichloride with the aryl Grignard reagent. 

Usually, after hydrolysis, the alcohol is the product, but sometimes (especially with aryl aldehydes) elimination follows directly and the product is an olefin. By the use of Bu,P along with Zn, the olefin can be made the main product,454 making this an alternative to the Wittig reaction (6-47). Since Grignard reagents cannot be formed from a-halo esters, the method is quite useful, though there are competing reactions and yields are sometimes low. A similar reaction (called the Blaise reaction) has been carried out on nitriles 455... 

The addition of Grignard reagents or organolithiums (alkenyl, alkyl, alkynyl, allyl or aryl) to nitroenamines (281)213 was reported by Severin to afford P-substituted-a-nitroalkenes.214 b Similarly, ketone enolates (sodium or potassium), ester enolates (lithium) and lactone enolates (lithium) react to afford acr-nitroethylidene salts (294) which, on hydrolysis with either silica gel or dilute acid, afford 7-keto-a,(3-unsaturated esters or ketones (295)2l4c-d or acylidene lactones (296).214 Alternatively, the salts (294, X s CH2) can be converted to -y-ketoketones (297) with ascorbic acid and copper catalyst. 

ArMgBr —> ArOH. The reagent converts an arylmagnesium bromide or an aryl-lithium into an ate complex (a), which rearranges to b. Phenols are obtained on acid-catalyzed hydrolysis of b. Yields are usually higher from Grignard reagents they are poor with sterically hindered substrates. 

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