Palladium-acetate catalyst for regioselective direct arylation at C2 of 3-furanyl or 3-thiophenyl acrylates with inhibition of Heck type reaction

Abstract

. Palladium-acetate catalyst for regioselective direct arylation at C2 of 3-furanyl or 3-thiophenyl acrylates with inhibition of Heck type reaction. Tetrahedron, Elsevier, 2013, 69 (22) Abstract: Pd(OAc)2 / KOAc was found to be an efficient catalytic system for the direct arylation of thiophene and furan derivatives bearing an acrylate at C3. The selectivity of the reaction strongly depends on the nature of the coordinating base. Na2CO3 and Li2CO3 favours the Heck type reaction; whereas the use of KOAc or CsOAc promotes regioselective arylation at C2 of the heteroarene and inhibits the Heck type reaction. The direct arylation products were obtained in moderate to good yields using only 0.1 mol% of catalyst. Electron-withdrawing substituent on aryl bromide such as acetyl, formyl, ester, nitrile or nitro, favours the reaction; whereas electron-donating ones are unfavourable.

Cross‐Coupling of Heteroarenes by CH Functionalization: Recent Progress towards Direct Arylation and Heteroarylation Reactions Involving Heteroarenes Containing One Heteroatom

“…[119] More recently, Doucet and co-workers established that C-2 arylation also occurs when methyl (E)-3-(thioA C H T U N G T R E N N U N G phen-3-yl)acrylate (170) is reacted with electronpoor aryl bromides and with 2-bromophenol in DMA at 130 8C in the presence of 0.1-0.5 mol% PdA C H T U N G T R E N N U N G (OAc) 2 and using KOAc as the base. [27] Compounds 171a-g were so obtained selectively in satisfactory yields (Table 5, entries 1-7). [27] However, the PdClA C H T U N G T R E N N U N G (C 3 H 5 )A C H T U N G T R E N N U N G (dppb)-catalyzed reaction of 170 with electron-poor aryl bromides using Na 2 CO 3 as the base led to the Heck-type compounds 172 in satisfactory yields (Scheme 80).…”

“…[27] Compounds 171a-g were so obtained selectively in satisfactory yields (Table 5, entries 1-7). [27] However, the PdClA C H T U N G T R E N N U N G (C 3 H 5 )A C H T U N G T R E N N U N G (dppb)-catalyzed reaction of 170 with electron-poor aryl bromides using Na 2 CO 3 as the base led to the Heck-type compounds 172 in satisfactory yields (Scheme 80). [27] This complete change in selectivity was ascribed to a stronger interaction of the Na + cation compared to that of the K + cation with the corresponding anions in DMA that should disadvantage a C À H concerted metalation-deprotonation mechanism.…”

“…[26] More recently, Doucet demonstrated that the PdA C H T U N G T R E N N U N G (OAc) 2 -catalyzed reaction of methyl (E)-3-(furan-3-yl)acrylate (39) with (hetero)aryl bromides under ligand-free conditions in DMA at 130 8C in the presence of KOAc as the base occurred selectively at C-2 to give compounds 40 in low to good yields (Table 1, entries [1][2][3][4][5][6][7][8][9][10][11]. [27] He also found that compounds 40e (entry 5, Table 1) and 40k (entry 11, Table 1) could not be obtained using 0.1 mol% PdA C H T U N G T R E N N U N G (OAc) 2 as the catalyst, but could be prepared in 16 and 58% yield,s respectively, by performing the arylation reactions at 150 8C in the presence of 2 mol% [35,40] as the catalyst. [27] Nevertheless, the PdCl-…”

“…[27] He also found that compounds 40e (entry 5, Table 1) and 40k (entry 11, Table 1) could not be obtained using 0.1 mol% PdA C H T U N G T R E N N U N G (OAc) 2 as the catalyst, but could be prepared in 16 and 58% yield,s respectively, by performing the arylation reactions at 150 8C in the presence of 2 mol% [35,40] as the catalyst. [27] Nevertheless, the PdCl-…”

Theoretical Study of Reaction Mechanism between N,N-Dimethyl acrylamide and Carbazole Derivatives Catalyzed by Palladium(II)

“…As a most valuable tool of activating the unreactive carbon-hydrogen bond, transition metal-catalyzed reactions have been extensively and systematically investigated [4,5]. Among transition metals, palladium shows an excellent catalytic performance for appropriate coordinating with all kinds of ligands, such as N-heterocyclic carbenes [6][7][8] and acetate [9][10][11][12] and it has become one of the most effective transition metal catalysts [13][14][15]. Palladium catalysts have been widely used in C-N coupling reactions, like Suzuki-Miyaura reaction [16][17][18], Heck-Mizoroki reaction [19][20][21][22], Stille reaction [23][24][25][26][27] and Sonogashira reaction [28][29][30].…”