Anilides triflation

Na2CC>3), 25 °C, 24 h. Larock extended his work in several ways [302-305], particularly with regard to Pd-catalyzed cross-coupling of o-allylic and o-vinylic anilides with vinyl halides and triflates to produce 2-vinylindoles [303-305], an example of which is shown [305]. The related "Larock indole synthesis" is discussed separately in the next section. 

A variety of five-membered nitrogen heterocycles can be prepared efficiently by inter- or intramolecular addition/cyclizations of sulfonamide anions with alkynyliodonium salts. The intermolecular variant employs the combination of the amides 172 or anilides 174 with propynyl(phenyl)iodonium triflate (Scheme 65) [131,132]. The yield of dihydropyrroles 173 in this cyclization is extremely sensitive to the nature of the protective group P the tosyl group in 172 proved... 

Shi has reported a method for /V-alkylanilidc arylation by simple arenes [53], The reaction conditions include heating the anilide with excess arene in propionic acid in the presence of catalytic palladium acetate and copper triflate under oxygen atmosphere. Use of monosubstituted arenes leads to the formation of isomer mixtures however, from the point of atom economy C-H/C-H couplings are the most efficient way for formation of C-C bonds if oxygen is used as the terminal oxidant. Shi has also reported that anilides can be coupled with arylboronic acids and trialkoxyaryl-silanes [54, 55], Silver and copper salts are used as terminal oxidants. 

Enol triflates are also excellent substrates in the Heck reaction. They may be prepared by the reaction of enolizable ketones with trifluoromethanesulphonic anhydride or the crystalline A, A -bis(trifluoromethanesulphonyl)anilide (A/ -phenyltriflide) [46]. The enol triflates derived from 2,2,6-trimethylcyclohexanone (90), from the r-butyldi methyl si lyl ether of 3-hydroxy-2,2,6-trimethylcyclohexanone (91), and from 2,2,5-trimethylcyclopentanone (92) couple in excellent yields (88-93%) to methyl vinyl ketone (10) in the presence of bis(triphenyl-phosphine)palladium(n) dichloride [PdCl2(PPh2)2l, to give p-ionone (2) [47], the 3-hydroxy-P-ionone derivative 93 [48], and the 5-membered-ring P-ionone analogue 94 [49], respectively (Scheme 22). 

Since acylated heteroaromatics are active intermediates for the synthesis of various pharmaceuticals, catalytic acylation of heteroaromatics using safe and reusable catalysts is important in pharmaceutical industry. It is found that gallium triflate can act as an efficient catalyst for Friedel-Crafts acylation of furan, pyrrole, and indole derivatives (eq 3-5). Friedel-Crafts acylation of acyl anilides using AICI3 requires a stoichiometric amount of the catalyst and the yields are low. Studies showed that catalytic acylation of aniline derivatives can be achieved in high yields using Ga(OTf)3 (10 mol%) in the presence of LiClOa (eq 6). ... 

---