Cross-coupling reactions acylation

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. 

Tributylstannyl)-3-cyclobutene-1,2-diones and 4-methyl-3-(tributylstan-nyl)-3-cyclobutene-l,2-dione 2-ethylene acetals undergo the palladium/copper-catalyzed cross coupling with acyl halides, and palladium-catalyzed carbon-ylative cross coupling with aryl/heteroaryl iodides [45]. The coupling reaction of alkenyl (phenyl )iodonium triflates is also performed by a palladium/copper catalyst [46],... 

Trialkylvinylstannanes undergo cross-coupling reactions with acyl chlorides, as shown by reactions 58307 and 59308. These acylations can be conducted under reductive conditions to saturate the carbon-carbon double bond, as illustrated in reaction 60309. Also... 

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... 

Reactions of Acylzirconocene Chlorides as "Unmasked Acyl Group Donors 5.4.4.5 Cu-catalyzed cross-coupling reactions... 

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... 

For reviews of the Pd-catalyzed acylation and other cross-coupling reactions with a-hetero-substituted organic electrophiles, see ... 

An acyl-palladium complex might undergo a series of follow up reactions. Subsequent transmetalation and reductive elimination lead to the formation of a carbonyl compound. This process is also coined carbonylative coupling, referring to the cross-coupling reaction, which would take place in the absence of carbon monoxide under similar conditions (for more details see Chapter 2.4.). 

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. 

Decarbonylative cross coupling of acyl halides.8 This unusual reaction is observed on coupling aroyl chlorides with alkyl(phenyl)acetyl chlorides in the pres-... 

Table 5.11 Range of acyl chlorides and sulfonates in iron-catalyzed cross-coupling reactions.

Scheme8.3. Simplified mechanism of Pd-catalyzed cross-coupling reactions. R, R = aryl, vinyl, a I kynyl, allyl, benzyl, alkyl, acyl ...

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

The lithiation of an O-vinyl carbamate with rAr-BuLi followed by transmetallation with zinc bromide provides the convenient acyl anion derivative, which undergoes smooth Pd(0)-catalyzed cross-coupling reactions (Equation (24)).67 This reaction sequence has been extended to lithium enolates. The deprotonation of the aminoester with LDA followed by a transmetallation with zinc bromide in ether furnishes a zinc enolate, which readily adds to the double... 

Lithiation of compound 560 with s-BuLi-TMEDA in THF at —78 °C following an inverse addition protocol provided the anion 561. It reacts with primary alkyl iodides and triflates, silyl chlorides, diphenyl disulfide, epoxides, aldehydes, ketones, imines, acyl chlorides, isocyanates and sulfonyl fluorides to yield the expected compounds 562 (Scheme 152). The transmetallation of compound 561 with ZnBr2 allowed the palladium-catalyzed cross-coupling reaction with aryl and vinyl bromides837. When the reaction was quenched with 1,2-dibromotetrafluoroethane, the corresponding bromide 562 (X = Br) is obtained838. 

Another method of benzannulation to a furan ring uses precursors of type 59, which are available by cross-coupling reaction with the corresponding 3-bromofuran. Upon treatment with ethyl chloroformate and triethylamine, a pyrocarbonate is formed which acylates the furan nucleus in an intramolecular reaction. With an excess base the 7-hydroxybenzofurans are obtained (Equation 123) <1998TL5609>. 

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