Acyliron 1,4-addition with

The acyliron(0) complex (102) has been isolated and subjected to the same nucleophilic displacement (or equivalently oxidative addition) with excellent correlation (Scheme 39). The same species is also readily available from acid chlorides (i.e. formation of 103), but the overall process has not been widely used in the synthesis of ketones (Scheme 40). The final step of the process, a reductive elimination of acyliron(II) complex (104) or (105), is quite rapid and it has not been possible to isolate and identify the presumed intermediates in this case (Scheme 41). Since the oxidative addition of the acyliron complex with the alkyl halide is extremely mild, the corresponding ketone formed in the reaction is not subject to attack by organometallic reagents and no tertiary tdcohol is formed. 

Palladium(O) complexes are well known to suffer oxidative addition with acid chlorides. The resulting acylpalladium(Il) complex (106) is, in contrast to the acyliron(II) complex discussed above, an electrophilic species which is subject to nucleophilic attack by various organometallics. Stille has studied the ad tion of organotins because they undergo rapid nucleophilic addition to the acylpalladium(II) complex, but do not add to either the acid chloride or react with the ketone (Scheme 42). There are also several other organometallics useful in this sense vide irfra). 

Potassium tetracarbonylferratej 18 cr own-6 poly ether 1,4-Addition with acyliron complexes... 

Addition of nucleophiles to a carbon monoxide ligand of pentacarbonyliron provides anionic acyliron intermediates which can be trapped by electrophiles (H+ or R—X) to furnish aldehydes or ketones [18]. However, carbonyl insertion into alkyl halides using iron carbonyl complexes is more efficiently achieved with disodium tetracarbonylferrate (Collman s reagent) and provides unsymmetrical ketones (Scheme 1.2) [19, 20]. Collman s reagent is extremely sensitive towards air and moisture, but offers a great synthetic potential as carbonyl transfer reagent. It can be prepared by an in situ procedure starting from Fe(CO)5 and Na-naphthalene [20]. 

Michael addition to a,P-unsaturated acyliron complexes can be carried out with enantiopure lithium (a-methylbenzyl)allylamide in a stereoselective fashion to afford... 

Acyclic (ri -diene)iron complexes will give substituted cyclopentanones or y,5-unsaturated aldehydes upon treatment with nucleophiles under carbon monoxide atmosphere (Scheme 4-119). A proposed mechanism involves the addition of the nucleophile at an inner carbon atom of the t) -diene ligand followed by insertion of carbon monoxide. Subsequent protonation provides the unsaturated aldehyde. Alternatively, the acyliron intermediate can undergo carboferration to give an acyliron intermediate. Isomerization via (3-hydride elimination and readdition provides an iron-enolate anion that upon treatment with acid provides the cyclopentanone. ... 

Organozinc reagents are superior species for palladium- and nickel-catalyzed coupling reactions. This offers an exceptional method for the selective formation of sp -sp (eq 5), sp -sp (eqs 6 and 7), and sp -sp (eq 8) carbon-carbon bonds. In addition, the palladium-catalyzed coupling reactions of sp and sp halides with vinylalanes (eq 9), vinylcuprates, vinylzirconium (eq 10) and acyliron species often proceed more effectively in... 

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