Decomplexation, palladium complexes

Nickel and palladium complexes also catalyze the formation of the carbon-phosphorus bonds in phosphorus(V) and phosphorus(III) compounds. Indeed, this chemistry has become a common way to prepare phosphine ligands by the catalytic formation of phosphine oxides and subsequent reduction, by the formation of phosphine boranes and subsequent decomplexation, or by the formation of phosphines directly. The catalytic formation of both aryl and vinyl carbon phosphorus bonds has been accomplished. 

Oxidative Decomplexation of Nortricyclenones from Palladium Complexes with Collin s Reagent General Procedure ... 

Cyclopropanes can also be generated via decomplexation of cyclopropane containing allyl complexes of palladium. This reaction mode is represented by a palladium-catalyzed conversion of 1 -sulfonyloxy-1 -vinylcyclopropanes 6 or 1 -chlorovinylcyclopropanes, which, via nucleophilic substitution with allylic rearrangement, gave methylenecyclopropanes 7 with the heterofunction in the side chain.An allylic cyclopropane-containing palladium complex is suggested as the intermediate. -... 

Oxidative decomplexation of palladium complexes obtained via methanol addition to norbor-nadiene with Collin s reagent [chromium(Vl)oxide-pyridine)2] leads to norbornenones 32 and nortricyclenones 33. ... 

According to the mechanistic rationale given for the process [36], the reaction is supposed to proceed by NaHCOj-aided deprotonation of the allyl-CN substrate, which is assisted by the palladium atom of la (Figure 4.9). This process generates q -allyl complex 16, which readily reacts with electrophiles [39-41], such as 2a. t -Allyl palladium complexes preferentially react at the y-position of the aUylic moiety (17) to give the complex 18 [41, 42], which after decomplexation gives product 14a. 

Leung et al. [152-167] proposed the Diels-Alder reaction of phospholes with various dienophiles catalyzed by palladium complexes 235 as a method for the synthesis of chiral phosphines. The chiral compounds containing S)-ortho-(l-dimethylaminoethyl)-naphthalene palladium 235 were complexed with diene, for example with 3,4-dimethyl-1-phenylphosphole, which then entered into the Diels-Alder reaction with dienophiles (W,W-dimethylacrylamide, styrene, and others) to result in diastereoisomers of entio-amidophosphanorbomenon complexes 236 and 237. After separation, purification, and decomplexation, the... 

Deboronation of 22 in refluxing diethylamine affords 23 in quantitative yield whereas methylphosphinites 24-26 have been reported by Muller and co-workers after borane decomplexation with morpholine at room temperature. The absolute configuration of 24 was confirmed by the X-ray structure of a derived palladium complex. 

Copper(I) triflate was used as a co-catalyst in a palladium-catalyzed carbonylation reaction (Sch. 27). The copper Lewis acid was required for the transformation of homoallylic alcohol 118 to lactone 119. It was suggested that the CuOTf removes chloride from the organopalladium intermediate to effect olefin complexation and subsequent migratory insertion [60]. Copper(I) and copper(II) chlorides activate ruthenium alkylidene complexes for olefin metathesis by facilitating decomplexation of phosphines from the transition metal [61]. 

T-Bound cyclopropenylium cation complexes of palladium 4 were formed upon reaction of 1,1-dichlorocyclopropenes with palladium metal. Protonolysis resulted in decomplexation to give the free cyclopropenylium salt 5. ... 

Oxidative decomplexation of the above described palladium alkyl or allyl complexes with Collin s reagent gave norbornenones 20 and nortricyclenones 21 in varying ratios depending on the starting material. ... 

Partial reduction of dichloro(norbomadiene)palladium with sodium borohydride at — 40 C gave an intermediate 25 which could not be isolated but was assumed to be a homoallyl complex which upon reductive cleavage gave norbornene, norbomane and nortricyclene in a ratio of 9 7 1, while oxidative decomplexation gave norbornenone and nortricyclenone in a 1 1 ratio. ... 

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). ... 

Scheme 1.7 Formation of Pd-carbene complexes by reaction between palladium acetate and imidazolium salts followed by decomplexation at high temperature and formation of catalytically active PdNPs for Heck-type reactions [33e,i,jj.

Gomez and co-workers reported the preparation of tetradentate NPPN ligands 193. They were obtained as diastereomeric mixtures by reaction of diphosphides 191 with o-chlorooxazolines 192 in good yields. After careful recrystallisations of nickel complexes and decomplexation, two optically pure ligands could be obtained. Their coordination behaviour towards palladium was studied. ... 

Other metals besides palladium are also effective. Reaction of the cationic allyltetracarbonyUron complex derived from (1) or (2) with silyl enol ethers, O-sUyl ketene acetals, or allylstan-nanes, followed by oxidative decomplexation, gives the vinyl-sUane products. The process was shown to occur with near complete retention of stereochemistry (cf. eqs 4 and 5). ... 

---