Anion reactions with organic halides

Figure 4, Correlations of anion, radical, and radical anion reactions with organic halides and the halide effect...

Acidic chloroaluminate ionic liquids have already been described as both solvents and catalysts for reactions conventionally catalyzed by AICI3, such as catalytic Friedel-Crafts alkylation [35] or stoichiometric Friedel-Crafts acylation [36], in Section 5.1. In a very similar manner, Lewis-acidic transition metal complexes can form complex anions by reaction with organic halide salts. Seddon and co-workers, for example, patented a Friedel-Crafts acylation process based on an acidic chloro-ferrate ionic liquid catalyst [37]. 

MgCl+ ions undergo anion abstraction reactions with organic halides (equation and nitric acid (equation 31). 

TBAF has been modified structurally around the anion to reduce its hygroscopic property. Several such reagents have been reported and their reaction with organic halides and sulfonate esters have been described. Tetrabutylammonium difluoride is ascribed to be a stable reagent and easily displaces halides and sulfonate esters.215 1-Dodecyl tosylate (18) is thus converted into 1-fluorododecane (19) in 96% yield. 

We have now succeeded in the development of two new methods for the preparation of organofunctional silanes, both involving electroreductive coupling. The first synthesis concept comprises the anionic cleavage of electrochemically formed disilanes and subsequent reaction with organic halides, whereas the second even more general route involves the direct electrochemical Si-C bond formation. 

Anionic complexes, particularly those possessing low oxidation states, afford compounds with M —C C7 bonds via reaction with organic halides ... 

Trimethylsilyl)vinylketene (95) is stable and a reactive enophile in [4 + 2]cycloadditions. Trimethylsilylallenes have been used (Scheme 18) in the stereoselective synthesis of rra/t5-a,/3-unsaturated carbonyl compounds they have also been used to prepare the acetylenes (96) and (97) from ethylenic acylcyanides and carbonyl compounds/ respectively. In the presence of KF-18-crown-6, benzoyl trimethylsilanes (PhCOSiMea) behave as acyl anion equivalents in their reaction with organic halides to give ketones, ... 

Radical, Anion, Anion-Radical Reactions with Organic Halides... 

Because etiolate anions are sources of nucleophilic carbon one potential use m organic syn thesis IS their reaction with alkyl halides to give a alkyl denvahves of aldehydes and ketones... 

Thallium(i) salts have long been used in reactions with organic and organometallic halide complexes as a means of activating the halide by removal as insoluble T1X. However, the thallium ions proved not to be innocent bystanders, and numerous examples were reported in COMC (1995) where the metal-bound thallium complexes were formed. Deliberate reactions of thallium(i) and thallium(m) salts with metal carbonyl anions have yielded a variety of complexes of the form T1 MLJ3. In the past decade, new examples of metal carbonyl derivatives of thallium have been prepared (see Table 2). In addition, the propensity for Tl+ to form adducts with 16-electron noble metal complexes has been exploited. 

Reaction of interlayer anions with organic halides... 

The anionic hydrido carbonyls have been much studied because of their intermediacy in catalytic processes like the water gas shift reaction, reduction of organic substances, and other reactions. Thus chromium group hydrides [HM(CO)4PR3] are highly efficient H-transfer agents and for reactions with alkyl halides a reactivity order was established cii-[HW(CO)4PR3] > m-[HCr(CO)4PR3] > [HW(CO)5]... 

The reaction occurs well below the temperature at which most of the parent metal carbonyls exchange with free CO and so is a direct nucleophilic attack on coordinated CO, although it may alternatively proceed via a prior electron path. The resulting acyl anions can be isolated as their [R4N] " or [ (C6H5)3P 2N] salts but are reactive and are used directly in subsequent alkylations with organic halides, acetylenes, a-/i-unsaturated carbonyls and alkyloxonium salts to form organic condensation products or metal-carbene complexes. 

The anions generated from tetracaibonyl(phosphine) carbene complexes are more reactive in their reactions with organic electrophiles. This is consistent with the observation that the p/iTa of the methyl pentacarbonyl complex (88a) is increased by six orders of magnitude when one of the carbon monoxi ligands is replaced with tributylphosphine. The anion generated fr-om (106) will give good yields of alkylated products with simple alkyl halides such as ethyl bromide however, dialkylation is still a serious side reaction. It has been reported that both pentacarbonyl and tetracarbonyl(phosphine) complexes can be efficiently monoalkylated with alkyl triflates (primary and secondary). The anion (89) for example, can be monoalkyated with the 3-butenyl triflate in 80% yield. ... 

Oxidative Addition. C and Q are both greater in the product than in the starting material. Reactions of metal carbonyl anions with organic halides to form cr-bonded alkyl derivatives fall into this category. Thus, the Mn(CO)5 anion (C = 5, Q = —1) reacts with methyl iodide to form CH3Mn(CO)5 (C = 6, Q = 0) according to the following equation ... 

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