Reductive decomplexation

To solve this problem, we modified the steps as show in Figure 6, where the methyl group be introduced after epimerization of the dicobalthexacarbonyl complex 25 which may give a 1 4 mixture of 25 and 26 through our previous study (10). In addition, we have recently developed a new reductive decomplexation method of bis-cobalthexacarbonyl complex, which is applicable to the synthesis of 27 in a single step from bis-cobalthexacarbonyl complex 26... 

A number of reductive decomplexation methods are available. A reductive removal using tributyltinhydride to give the saturated hydrocarbon has been reported (Scheme 192). Reductive decomplexation has also been observed using trifluoro acetic acid to afford a cis-alkene as the major product (Scheme 193). 

A reductive removal of a propargylic hydroxy group using triethyl silane followed by a reductive decomplexation... 

Reductive decomplexation/ Although the common practice for removal of the hexacarbonyldicobalt residue from alkyne complexes involves mild oxidants, it is also possible to convert the complexes to free (Z)-alkenes with BUjSnH. If triethylsilane is used the decomplexation is followed by in situ hydrosilylation. 

Photochemical reductive decomplexation in the presence of acetic acid converted the tricar-bonyliron complex of cyclopropanated tropone 26 to bicyclo[5.1.0]oct-4-en-2-one (27) in 90% yield. 

Norbornadiene complexes of platinum and palladium react with silver carboxylates to form the carboxymetallation products 29 which upon treatment with triphenylphosphane undergo intramolecular alkene insertion into the metal-alkyl bond to form nortricyclene 30. Reductive decomplexation leads to acylated nortricyclenol 31 (exu-tricyclo[2.2.1.0 ]heptan-3-ol). ... 

It has often been loosely stated that a wide variety of reactions involving the reactants, ligands, and/or solvents present in a given reaction mixture would reduce Pd(II) species and that deliberate reduction of Pd(II) species by externally added reducing agents is unnecessary in most cases, hi fact, this statement is true. If so, what actually reduces Pd(II) species and how Inspection of Table 3 indicates that only reductive elimination, reductive decomplexation, and some processes involving nucleophilic attack on ligands can reduce Pd(II) species. 

Treatment of highly strained hydrocarbons with Pd complexes has been shown to induce valence bond isomerization. Some representative examples are shown in Scheme 4. The mechanisms of these reactions are not clear in most cases. However, a mechanism involving oxidative complexation, allylic rearrangement, and reductive decomplexation may be proposed for the Dewar benzene-to-benzene rearrangement. 

When combined with reductive decomplexation methods, the Nicholas reaction has found extensive use in the synthesis of marine polyether ladder toxins, such as ciguatoxin (Scheme 7.7). ... 

The value of the metal complexation results from control of the reaction, rather than any activation, Lewis acids being excellent catalysts for diene polymerization. Friedel-Crafts acylations of diene complexes have been used for the preparation of dienes, with decomplexation following carbonyl reduction. Decomplexation to afford dienones has been less explored. The intermediate cationic o -complex on treatment with triethyl phosphite or triphenylphosphine affords metal-free p,7-unsaturated phospho-nates or phosphonium salts (Scheme 19). The initial s-cis conformation of the diene fragment of the... 

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