Palladium alkyl electrophiles

Negishi E, Tan Z (2005) Diastereoselective, Enantioselective, and Regioselective Carbo-alumination Reactions Catalyzed by Zirconocene Derivatives. 8 139-176 Netherton M, Fu GC (2005)Palladium-catalyzed Cross-Coupling Reactions of Unactivated Alkyl Electrophiles with Organometallic Compounds. 14 85-108 NicolaouKC, KingNP, He Y (1998) Ring-Closing Metathesis in the Synthesis of EpothUones and Polyether Natural Products. 1 73-104 Nishiyama H (2004) Cyclopropanation with Ruthenium Catalysts. 11 81-92 Noels A, Demonceau A, Delaude L (2004) Ruthenium Promoted Catalysed Radical Processes toward Fine Chemistry. 11 155-171... 

Netherton M, Fu GC (2005) Palladium-catalyzed Cross-Coupling Reactions of Unactivated Alkyl Electrophiles with Organometallic Compounds. 14 85-108 Neumann H, see Jacobi von Wangelin A (2006) 18 207-221... 

Palladium- or nickel-catalyzed cross-coupling reactions Use of Alkyl Electrophiles Containing I, Br, Cl, and OTs... 

Abstract For many years, unactivated alkyl electrophiles that contain p hydrogens were generally regarded as unsuitable partners for palladium-catalyzed cross-coupling reactions. Recently, however, a series of studies have established that palladium complexes can in fact couple a range of alkyl electrophiles with a variety of organometallic reagents. 

Palladium-Catalyzed Cross-Coupling Reactions of Unactivated Alkyl Electrophiles 87... 

Due to concern about these issues, in combination with early interest and success in coupling aryl and vinyl electrophiles, progress toward the development of palladium- or nickel-based methods for cross-coupling alkyl halides/ sulfonates has been relatively slow. However, during the past decade (particularly the last few years), important advances have been described that clearly demonstrate that the aforementioned obstacles can be overcome and that the development of general catalysts for coupling alkyl electrophiles is a realistic objective. 

The Suzuki cross-coupling methods described in Sect. 2.1 establish that palladium complexes that bear electron-rich trialkylphosphines of the appropriate size can serve as effective catalysts for reactions of alkyl electrophiles. Naturally, it was of interest to determine if non-phosphine ligands that are bulky and electron-rich can also furnish active catalysts. 

Two reports have described palladium-catalyzed Stille cross-couplings of unactivated alkyl electrophiles. Specifically, these investigations by Fu demonstrate that primary alkyl bromides and iodides can be coupled with vinylstannanes [27,28] and arylstannanes [28] (Eq. 10). 

Representative examples of the application of Pd/PCy3 to Kumada-Mura-hashi couplings of primary alkyl chlorides are illustrated in Table 8 (entries 1-5). In contrast to most other palladium-based methods for cross-coupling alkyl electrophiles, the reaction proceeds well even for a p-branched alkyl halide (entry 2). 

III.2.11 Palladium- Catalyzed Cross-Coupling Involving Alkylmetals or Alkyl Electrophiles... 

Since the reaction can proceed at ambient temperature, some electrophilic functional groups can be present in the alkyl electrophiles, as exempUfied by products 1-3. Further optimizations studies on this catalyst led to the development of N-heterocychc carbene (NHC)-derived palladium catalysts for arylations of alkyl chlorides. In this system, it is assumed that the initial reaction of a precatalyst [Pd(IMes)(NQ)]2 4 and an aryl Grignard reagent should generate a coordinatively unsaturated palladium-carbene complex, which is the actual palladium-catalysis complex with high catalytic activity [9]. 

There has been a wide-ranging review of transmetalation reactions of arenes concentrating on the use of boron-containing compounds. The reaction of arylboronate esters and related compounds with alkyl halides is catalysed by copper(I) formation of an aryl—copper intermediate followed by an 5N2-type reaction with the alkyl electrophile is likely. Palladium complexed with a diimine is an excellent catalyst in the phenylation reaction of Michael acceptors with phenylboronic acid so as to yield products such as (16). The nickel-catalysed reaction of phenylboronic acid with styryl epoxides has been shown to yield a-substituted alcohols such as (17). 

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