Aryl complexes fluoro

Treatment of Ir(CO)Cl(PPh3)2 (29) with alkyl or aryl grignard reagents produces the corresponding alkyl or aryl iridium complexes R-Ir(CO)(PPh3)2 (63). These compounds are substantially more stable than the frilly phosphinated alkyl iridium compounds. The stability of these compounds also increases in the order aryl > alkyl with the fluoro substituted aryl complexes being the most stable. 

The exclusive access to the particular diastereomer of the NHC ligand (Ra,Ra) that behaves well in catalysis was later reported by the same group. After testing several substitution patterns, Dorta and coworkers foimd that placing a relatively rigid cydooctyl group at the 2-position of the naphthyl moieties lead to the dia-stereomerically pure NHC salt 74 and subsequently the palladium complex 75 (Scheme 3.41) [67]. The palladium complex 75 was tested in the a-arylation of amide for the synthesis of chiral 3-aryl-3-fluoro-oxindole 76. While moderate to... 

Activation of aromatic compounds by transition-metal complexes was initially studied with Cr(CO)3 complexes. Nucleophilic addition of 2-lithio-l,3-dithianes to arene-chromium(O) complexes 185 followed usually by iodine-promoted decomplexation affords the corresponding 2-arylated 1,3-dithianes 186. The reaction of //-(toluene)- and (anisole)tricarbonylchromium (185) with compound 161 gave mixtures (52 46 and 10 90, respectively) of ortho and meta substituted derivatives (186) (Scheme 54)244. The meta directing effect was also observed (mainly better than 95%) with amino and fluoro substituted complexes245. 

The cross-coupling reaction of alkenyl(fluoro)silanes with aryl halides sometimes produces, in addition to the desired ipso-cowpled products, small amounts of cmc-coupled products [14]. The czne-coupling is often striking in the reaction with organotin compounds. The isomer ratio of products produced by the reaction of l-fluoro(dimethyl)silyl-l-phenylethene with aryl iodides is found to depend on the electronic nature of a substituent on aryl iodides (Eq. 11) an electron-withdrawing group like trifluoromethyl and acetyl favors the formation of the ipso-coupled product. To explain the substituent effect, the mechanism depicted in Scheme 3 is proposed for the transmetalation of alkenylsilanes with palladium(ll) complexes. It is considered that an electron-donating substituent on Ar enhances... 

Dinitrogen trioxide-Boron trifluoride, NjOs-BF.,. The components react at —70 to form a stable white 1 1 complex. It is a weak nitrating agent but a powerful diazo-tizing agent in nonaqueous solution (benzene, chloroform). The diazonium salt which separates as a solid can be thermally decomposed to form fluoro derivatives (Schiemann reaction) or used in Gomberg-Bachmann arylation. 

Oxidation of trifluorophosphine by halogens is well known (282) and although corresponding reactions with alkyl or aryl fluorophosphines have received only little attention, it has become apparent that oxidation to the pentavalent phosphorus fluorides can be brought about by a wide variety of reagents. In certain cases the reducing property of the fluoro-phosphine has been utilized in the synthesis of zero-valent transition metal fluorophosphine complexes (Section IX). 

The reaction of nucleophiles with chloroarene-Mn(CO)3 and fluoro arene-Cr(CO)3 complexes has been employed for the synthesis of diaryl ethers and has been particularly applied (ref. 55) to the selective arylation of polyfunctional phenols by reaction of the phenoxide formed from NaH in dimethylformamide with the 4-chlorotoluene-manganese tricarbonyl cation (as the hexafluorophosphate) in acetonitrile at ambient temperature over 18 hours. 

The so far most advanced protocol employs a catalyst based on nickel instead of palladium, and the BlNAP-complex 5 of nickel dichloride was identified as a suitable catalyst precursor [36]. The resulting catalysis readily converts ester equivalents into the corresponding monofluorinated derivatives. No difluorinated product is formed and the reaction proceeds with good to very good enantiomeric excesses of up to 88%, with no racemization encountered under the chosen conditions. Importantly, the thiazolidinone group could readily be removed within a two-step procedure as demonstrated for the phenyl-substituted product. Hence, enantiomerically enriched a-fluoro aryl acetates are now available from this protocol. 

Fig. 1 Proposed cationic Pd(IV) intermediate in the reductive elimination of Aryl-I and Aryl-F in the reaction between the Pd(II) aryl iodo complexes and A-fluoro-2,4,6-collidinium cation...

Scheme 23 Aryl-fluoride reductive elimination from an isolated Pd(IV) fluoro complex...

Oxidative addition of fluorinated aromatics to give metal(aryl) fluoro complexes has been observed frequently for complexes of group 10 metals, but rarely otherwise. The reactions include the insertion of an Ni(PEt3)2 unit into a carbon-fluorine bond in hexafluorobenzene (Scheme 5). The very slow conversion (4 weeks) was initially reported by Fahey and Mahan full spectroscopic and crystallographic characterization of the product was performed by Perutz et al " Mechanistic studies and density functional theory (DFT) calculations give strong evidence for precoordination of the aromatic substrate followed by a concerted oxidative addition. " " Oxidative addition has also been... 

Moore showed that a much more active alk)me metathesis catalyst than the trisamido species is generated from addition of electron-poor phenols to the trisamide complex containing a propyUdyne ligand (Equation 21.27 and Table 21.2). Studies of various aryl alcohol and fluoro-alcohol additives showed that the most reactive catalyst was generated from p-nitrophenol. ... 

C.ii.a. Silyl Derivatives. A Japanese gronp recently reported an original Pd-catalyzed reaction with vinyl- or aryl-fluoro silyl derivatives and vinyl epoxides. " A mechanism involving a zwitterionic TjLallylpalladinm silicate intermediate has been proposed (Scheme 5). Intramolecular transmetallation can give two 17 -allylorganopalladium complexes in equilibrium. The steric bulkiness of the phosphine ligand as well as its electronic affinity are responsible for the 1,2/1,4-product distribution. 

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