Alkene Acylation

FRIEDEL - CRAFTS Alkylation-Acylation Alkylation or acylation ol aromatic compounds by means of alryl halides, alcohols.alkenes, acyl halides in the presence of Lewis acids... 

Other functional groups provide sufficient stabilization of radicals to permit successful chain additions to alkenes. Acyl radicals are formed by abstraction of the formyl hydrogen from aldehydes. As indicated in Table 12.7, the resulting acyl radicals are... 

It has been suggested that the kinetic preference for formation of (3,y-unsaturated ketones results from an intramolecular deprotonation, as shown in the mechanism above.51 The carbonyl-ene and alkene acylation reactions have several similarities. Both reactions occur most effectively in intramolecular circumstances and provide a useful method for ring closure. Although both reactions appear to occur through highly polarized TSs, there is a strong tendency toward specificity in the proton abstraction step. This specificity and other similarities in the reaction are consistent with a cyclic formulation of the mechanism. 

Table 8. Cyclization of carboxylic acids onto alkenes acyl radical synthon...

Aiylisoquinolines can be prepared by Suzuki coupling of the 4-bromoderivatives <99JOC1407>. This methodology was used in the synthesis of dinapsoline. A synthesis of 4-alkylcarbonylmethylidene isoquinolines was reported using a modified Jones oxidation and alkene acylation conditions <99H(51)2311>. 

Alkene acylation may be used in the synthesis of cyclic products by appropriately selecting the alkene and the acid derivative. When a,P-unsaturated acid halides react with cycloalkenes, the intermediate undergoes cyclization to yield octalones and indanones 112... 

Significant advances resulting from the use of aluminosilicate solids were made during the last few years [3-6] and the first industrial application of zeolites in large scale Friedel-Crafts acylations was reported very recently [7]. However, most of the efforts devoted so far focused on the acylation of aromatic compounds. To the best of our knowledge, recourse to heterogeneous aluminosilicate catalysts for the acylation of alkenes has not yet been reported. Conventional methods for alkene acylation [8] involve the use of Br0nsted or Lewis acids such as sulfuric acid [9], boron trifluoride [10], zinc chloride [11], or... 

Previous results show the possibility of enolization during alkenes acylation. We may postulate that acylation with -alkenyl acyl chlorides could lead... 

Hydroformylation of PhCH=CHMe in the presence of RhCl(PPh3)3 produces PhCH(CHO)-CHa-CH3 and PhCH3-CH(CHO)-CH3, as well as some PhCH2 CH2 CH3. Both Rh4(CO)i2 and mixed carbonyl-phosphine complexes derived from Rh4(CO)i2 and from Rh,(CO)ie are active catalysts for hydroformylation of alkenes. Acyl-rhodium intermediates may be important when Rh4(COX2 is the catalyst, for [Rh-(C0)2(02CR)]2 dimers have been isolated from alkene hydroformylations in which this polynuclear carbonyl has been the catalyst. Rh4(CO)i2 also catalyses the reaction between ethylene and carbon monoxide, which produces several products, including octane-3,6-dione, undecane-3,6,9-trione, and tetradecane-3,6,9,12-tetraone. The products obtained indicate a mechanism in which addition of ethylene to rhodium and insertion of carbon monoxide into a rhodium-carbon bond alternate. ... 

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