Friedel copper catalyzed

Pyrrolo[l,2-a]indolequinones were prepared also by cyclization reactions. One of them involves copper-catalyzed pyrolysis of 2-azido-5-methoxy-6-methyl-3-(2,4-pentadienyl)-l,4-benzoquinone to give compound 45 (87JOC3956). The second pyrrole ring was also formed from a 2-hydroxy-propyl side chain of an indolo-4,7-dione (80JOC5057). Benzo analogs were prepared in a Friedel-Crafts reaction from either phthalic anhydride (67TL765) or 2-pyrrolidinylcarbonyl chloride (86H2797). 

One can indirectly substitute the pyridine ring with electrophiles by using an electron-rich dihydropyridine intermediate. Dihydropyridines 150 can be prepared by a one-pot synthesis utilizing a copper-catalyzed Grignard addition to l-(phenoxycarbonyl)pyridinium chloride (149). Dihydropyridines 150 undergo regiospecific Friedel-Crafts acylation in good yield with many... 

Xiao et al. developed a highly enantioselective, copper-catalyzed Friedel-Crafts alkylation/A7-hemiacetalization cascade reaction of indoles. Indole 184 was allowed to react with ester 185 to furnish fused indole 186 in excellent yield, diastereoselectivity, and enantioselectivity. Indole 186 was further elaborated to complete a formal synthesis of analogs of flinderoles B and C (13AG(I)3250). 

In 2006, Zhou s group reported a copper-catalyzed asymmetric synthesis (it was described in the paper as Friedel-Crafts-type reaction) using Al-sulfonyl aldimines with indoles to provide a simple approach to optically active 3-indolylmethanamine derivatives with high enantioselectivity. A bis-oxazoline-copper complex was used (Scheme 6.37) [50]. 

A Cul-catalyzed synthesis of acridones via intramolecular cyclization including C(sp )-H bond activation and C(0)-CHj bond cleavage process using air as the oxidant was reported in 2013 (Scheme 8.100). Many substituents on the aromatic rings are tolerable in the reaction, and the acridin-9(10//)-ones could be obtained in moderate to excellent yields. C-labeling experiments show that only about 86% of carbon atom of carbonyl originates from the substrate. They proposed that a copper-catalyzed intramolecular Friedel-Crafts-type reaction pathway is disfavored [172]. Shortly after the previous report, Fu and coworkers developed a relevant aerobic synthesis of acridone derivatives from l-[2-(arylamino)aryl]ethanones under Cu(02CCF3)2/pyridine/02 catalytic system [173]. 

Thioacetals eliminate to vinylsulfides in the presence of CuOTf (Scheme 46).192 Cu1 and Cu11 triflates are mild Lewis acids for Friedel-Crafts acylation and alkylation reactions. CuOTf effectively catalyzes the reaction of anisole with selenoesters.193,194 Copper(II) sulfate promotes epoxide ring opening reactions in the presence of pyridine,195 with retention of configuration being observed. Cu(OTf)2 is a catalyst for the ring opening of aziridine by aniline.196... 

Scheme 8.47 Copper/box-catalyzed enantioselective Friedel-Crafts atylation of imines 166.

SCHEME 10.24 Enantioselective Friedel-Crafts alkylation catalyzed by a chiral copper complex. 

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