Friedel-Crafl synthesis

Friedel-Crafls reactions Fnedlander reaction FnelAnder synthesis Fries rearrangement Frigen... 

Some pyrazole rings are electron-rich enough to undergo the Friedel-Crafts reaction. With the aid of AICI3 as the Lewis acid, the pyrazole below underwent the Friedel-Crafls aroylation widi o-fluorobenzoyl chloride to afford the ketone, an advanced intermediate for the synthesis of novel potential antipsychotic agents. ... 

Different reaction mechanisms are postulated for die synthesis of 2-or 4-quinolone derivatives. The Knorr reaction involves a nucleophilic attack of aniline nitrogen on the ester of P-ketoester component, providing anilide, which undergoes Friedel-Crafls cyclization followed by dehydration with sulfuric acid to yield 2-quinolones. On die other hand, a completely different pathway is involved in the case of Conrad-Limpach reaction. Condensation of aniline derivative with P-ketoester provides the corresponding enamino-ester. Enolization was followed by a 67c-electrocyclization reaction to form a 4-quinolone. A postulated alternative reaction padiway invokes the formation of an iminoketene prior to the cyclization step. 

C-acylation s. Friedel-Crafls ketone synthesis —, C-alkylation 21, 815 special s. diaryl. . . stilbenes styr. . . ... 

The Pechmann condensation served as a key ring-forming reaction in Xu and co-workers s synthesis of the HIV-1-selective nonnucleoside reverse transcriptase inhibitor calanolide A (39). In this work, phloroglucinol (35) and ethyl butyrylacetate (36) were condensed in sulfuric acid at 90 °C to provide 5,7-dihydroxy-4-propylcoumarin (37) in nearly quantitative yield on 150 g scale. Subsequent Friedel-Crafls acylation of 37 followed by condensation of the acylcoumarin product with 4,4-dimethoxy-2-methylbutan-2-ol provided pyranylcoumarin 38, which was converted to... 

Many of the more recent applications of intramolecular Friedel-Crafls acylation reactions have involved the synthesis of biologically active tetracycline derivatives. In the synthesis of aclacinomycin- - the acid shown in equation (42) was cyclized efficiently to the anthrone using trifluoroacetic anhydride in dichloromethane and then converted immediately into the anthraquinone shown. 

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