Acyl halides cross-coupling reactions

The cross-coupling reactions of benzylic halides and acyl halides produced the expected ketones in good to high yields(39,47). The present method can supplement the corresponding Grignard reaction, which does not work well since benzylmagnesium halides undergo dimerization readily. 

In the Pd-catalyzed cross-coupling reactions of acylzirconocene chlorides with allylic halides and/or acetates (Section 5.4.4.4), the isolation of the expected p,y-unsaturated ketone is hampered by the formation of the a, P-un saturated ketone, which arises from isomerization of the p,y-double bond. This undesirable formation of the unsaturated ketone can be avoided by the use of a Cu(I) catalyst instead of a Pd catalyst [35], Most Cu(I) salts, with the exception of CuBr - SMe2, can be used as efficient catalysts Thus the reactions of acylzirconocene chlorides with allyl compounds (Table 5 8 and Scheme 5 30) or propargyl halides (Table 5.9) in the presence of a catalytic amount (10 mol%) of Cu(I) in DMF or THF are completed within 1 h at 0°C to give ffie acyl--allyl or acyl-allenyl coupled products, respectively, in good yields. ill... 

The relative weakness of the carbon-tin bond provided a useful method for carbon-carbon bond formation by cross-coupling reaction with acyl halides. This reaction has been applied for the two-step synthesis of a-ketocyclopropyl sulfones (equation 8)30. 

H. Cross-coupling Reactions with Acyl Halides. 1291... 

Very recently, arylboronic esters have been directly obtained from aiyl halides via the cross-coupling reaction of (tetraalkoxy)diboron (Scheme 2-7) [28]. The reaction tolerates various functional groups such as ester, nitrile, nitro, and acyl groups. 

Decarbonylative cross coupling of acyl halides. This unusual reaction is observed on coupling aroyl chlorides with alkyl(phenyl)acetyl chlorides in the pres-... 

Various Pd-catalyzed carbonylation reactions have often been referred to as carbonyla-tive cross-coupling reactions (Scheme 4). However, these reactions involving the formation of two C—C bonds with incorporation of CO clearly display a pattern of chemical transformation that is different from Scheme 1. So, these reactions are discussed in Parts VI and VIII. On the other hand, Pd-catalyzed acylation with acyl halides and related derivatives are examples of the reaction represented by Scheme 1, where is acyl, and they are therefore discussed in this Part (Sect. III.2.12.1), even if CO may be used to prevent decarbonylation. 

The Pd-catalyzed cross-coupling reaction of an organobismuth compound was first recorded by Barton and co-workers in 1988. Thus, the reaction of triphenylbismuth with acyl halides took place in the presence of catalytic amounts of Pd(OAc>2 and... 

First, coordinatively unsaturated active palladium catalyst, PdL2, is produced via dissociation of the ligands, which then reacts with acyl halide to give the acylpalladium intermediate. Since deinsertion of CO of the acylpalladium derivatives may occur simul-taneously, the next step, transmetallation (so-called metathesis), is the most crucial for the efficiency of the overall reaction. A variety of organometallic compounds, such as boron, aluminum, copper, zinc, mercury, silicon, tin, lead, zirconium, and bismuth, are used as the partner in this coupling reaction without loss of CO. In this section, the important features of the cross-coupling reactions of a variety of organometallic compounds with acyl halides and related electrophiles are discussed. 

Organozirconium compounds also undergo the Pd-catalyzed cross-coupling reaction with acyl halides.h i in the presence of ZnCF, the reaction can be carried out more efficiently. Acykirconium species, which are produced via hydrozirconation of alkynes or alkenes by zirconocene hydrochloride followed by insertion of CO, couple with acyl chlorides to give a-diketones (Scheme 12). 

The Negishi cross-coupling reaction is the nickel- or palladium-catalyzed coupling of organozinc compounds with various halides or triflates (aryl, alkenyl, all nyl, and acyl). 

Pd-catalyzed cross-coupling reactions of organozinc compounds with alkenyl and aryl halides can be carried out under mild conditions and are the fastest among all reactions using various organometallics. The reaction with acyl hahdes is not an exception. Usually, the reaction is completed at lower than room temperature within a couple of hours [38,251 - 25 3]. As organozinc compounds are coordinatively unsaturated and sterically less bulky, the transmetallation step is facilitated [29] ... 

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