Grignard-type reactions organic halides

Organic halides play a fundamental role in organic chemistry. These compounds are important precursors for carbocations, carbanions, radicals, and carbenes and thus serve as an important platform for organic functional group transformations. Many classical reactions involve the reactions of organic halides. Examples of these reactions include the nucleophilic substitution reactions, elimination reactions, Grignard-type reactions, various transition-metal catalyzed coupling reactions, carbene-related cyclopropanations reactions, and radical cyclization reactions. All these reactions can be carried out in aqueous media. 

The conventional Grignard reaction (Fig. 2, route I) would generate both a stoichiometric amount of halide waste and a stoichiometric amount of metal waste. It also requires multistep synthesis of the halides. On the other hand, an alternative Grignard-type reaction via catalytic C-H activation in water (Fig. 2, route II) would preclude the use of flammable organic solvents and also avoid the wasteful process of drying them. Obviously, it would provide a cleaner solution for organic synthesis and provide a theoretical 100% atom-efficiency. 

Of further interest is a comparison [81b] of the structure-reactivity profile for several reaction types (Fig. 3), such as (1) the Grignard reagent of organic halides with magnesium,... 

We reported that smooth oxidative addition of organic halides such as aryl, benzyl, and allyl halides to metallic nickel proceeded to afford organonickel halides under mild conditions, which yielded homocoupled products [11, 41] or ketones by the reaction with acid chlorides [42] or alkyl oxalyl chlorides [43]. We describe here a new method for the preparation of 3-aryl-2-hydroxy-l-propanones (4) in good yield by the Grignard-type addition of benzyl halides to 1,2-diketones mediated by metallic nickel under neutral conditions [44]. 

A solution of the divalent lanthanide derivative Sml2 may be prepared under mild conditions [equation (9)], and among a variety of reactions reported for this reagent are the reduction of aldehydes in the presence of ketones, and the reductive alkylation of ketones by organic halides or sulphonates [equation (10)]. The reagent solution can be easily stored under nitrogen, especially in the presence of small amounts of the metal (Sm), and Grignard -type apparatus is adequate for the reactions, which are usually clean. 

The reaction is applicable to various types of Grignard reagents (e.g. aryl, alkyl) and organic halides bearing a C pi-carbon (e.g. aryl, vinyl). The reactivity order of the halide component was found to be Ar—I > Ar-Br > Ar-Cl > Ar-F. Grignard reagents are equally prepared either in Et20 or in THF, however, the... 

Grignard reagents, organomagnesium halides, are prepared by the reaction of metallic magnesium with a wide range of organic halides (reaction 9.3). Dry ether type solvents are essential. 

Structural types for organometallic rhodium and iridium porphyrins mostly comprise five- or six-coordinate complexes (Por)M(R) or (Por)M(R)(L), where R is a (T-bonded alkyl, aryl, or other organic fragment, and Lisa neutral donor. Most examples contain rhodium, and the chemistry of the corresponding iridium porphyrins is much more scarce. The classical methods of preparation of these complexes involves either reaction of Rh(III) halides Rh(Por)X with organolithium or Grignard reagents, or reaction of Rh(I) anions [Rh(Por)] with alkyl or aryl halides. In this sense the chemistry parallels that of iron and cobalt porphyrins. 

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