Cross-coupling reactions thioesters

Iron-catalyzed cross-coupling reactions of various acyl chlorides or thioesters with Grignard reagents have been pioneered by Marchese et al. and other research groups.322 These transformations provide general and convenient access to a wide range of ketones and have been further extended to the use of a supported iron(lll) complex.323... 

Thioesters have been used for carbon-carbon bond formation in transition metal-catalysed Grignard reactions. In the accompanying scheme two sequential cross-coupling reactions with 5-phenvl carbonochloridothioate and Grignard reagents led to a general and efficient ketone synthesis [377,378]. 

In 1998, Fukuyama reported on the cross-coupling of thioesters with zinc reagents to give unsymmetrical ketones (Scheme 5-101). The advantages are high chemoselectivity, mild reaction conditions, and the use of less-toxic reagents. One asset of this method is that the reaction stops at the ketone and does not proceed to a tertiary alcohol. In addition, the protocol is compatible with functional groups such as ketones, acetates, sulfides, aromatic bromides, chlorides, and aldehydes. 

Several related cross-couplings that involve both catalytic levels of Pd and Cu have also been reported, such as Hecklike reactions see Heck Reaction) of vinyl esters with arylstannanes (equation 6), aryl selenenylations between BusSnSeAr and aryl halides (equation 7), and thioarene or thioester couplings to aryl, vinyl, or alkyl stannanes (equation 8). ... 

Thioesters are readily accessible and have recently been shown to undergo Pd-catalyzed cross coupling with boronic acids to prepare ketone products. This chemistry has expanded to Stille cross coupling. The key to the reaction is the addition of stoichiometric amounts of Cu -diphenylphosphinate [60]. Stille coupling of thioester 142 with 2-tributylstannylpyrimidine affords the desired product 143 in 61% isolate yield. 

The reaction of thioesters in the presence of nonpyrophoric Pd(OH)2/C (Pearlman s catalyst) with various functionalized organozinc halides such as 457 leads to functionalized unsynunetrical ketones such as 458 in high yields (Fukuyama reaction. Scheme 2-139, eq. (a)). This catalyst can also be used for Sonogashira and Suzuki reactions. Thus, the Ni(acac)2-catalyzed cross-coupling of a functionalized zinc reagent 457 with various thioesters like 459 provides under mild conditions the desired acylation... 

Cross coupling of EtsAl with aryl phosphates or alkynyl bromides proceeds with a Ni catalyst to provide alkylated arenes or aUrynes (eqs 5 and 6). While Pd or Cu complexes are used as the catalyst for the coupling of EtsAl with carboxylic acid chlorides or thioesters (eq 7), Iron(HI) Chloride is used for reactions of propargyl acetates to give substituted allenes (eq 8)."... 

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