Cross‐Coupling of Triallyl(aryl)silanes with Aryl Bromides and Chlorides: An Alternative Convenient Biaryl Synthesis

Abstract

Cross-coupling of a diverse range of aryl bromides with triallyl(aryl)silanes is effective in the presence of PdCl 2 /PCy 3 and tetrabutylammonium fluoride (TBAF) in DMSO-H 2 O to give various biaryls in good yields. It is worthwhile to note that the all-carbon-substituted arylsilanes, stable towards moisture, acid, and base and easily accessible, serve as a highly practical alternative to their aryl(halo)silane counterparts. A catalyst system consisting of [(h 3 -C 3 H 5 )PdCl] 2 and 2-[2,4,6-(i-Pr) 3 C 6 H 2 ]-C 6 H 4 PCy 2 and use of TBAF · 3 H 2 O in THF-H 2 O are effective especially for the cross-coupling with aryl chlorides. Both of the catalyst systems tolerate a broad spectrum of common functional groups. The high efficiency of reactions is presumably due to the ready cleavage of the allyl groups upon treatment with TBAF · 3 H 2 O and an appropriate amount of water. Diallyl(diphenyl)silane also cross-couples with various aryl bromides and chlorides in good yields, whereas allyl(triphenyl)silane gives the cross-coupled products in only moderate yields. Through sequential cross-coupling of bromochlorobenzenes with different arylsilanes, a range of unsymmetrical terphenyls are accessible in good overall yields.

Biaryl Phosphane Ligands in Palladium‐Catalyzed Amination

“…[2] These phosphines have been used as ligands for gold, [3][4][5][6][7][8][9][10][11] silver, [12] rhodium, [13,14] ruthenium [15][16][17] and copper [18] where they have been shown to impart improvements in reactivity and catalyst stability. It is in reactions catalyzed by palladium, however, that they have had by far the greatest impact including the Sonogashira, [19] Negishi, [20] Hiyama, [21][22][23] Kumada [24] and Suzuki [25][26][27][28][29][30] cross-coupling reactions, Heck reaction, [31][32][33] enolate arylation [34][35][36][37] and allylation, [38] reductive cyclization [39] and etherification, [40][41][42][43] silylation, [44] borylation, [45][46][47] cyanation, [48,…”

Chemoselective Transfer of Allyl or Phenyl Group from Allyl(phenyl)germanes in Pd-catalyzed Reactions with Aryl Halides

“…17 Hiyama and co-workers utilized tri-, di-, and monoallyl(aryl)-silanes in Pd-coupling with aryl halides to access biaryls. 18 They suggested that allylsilanes spontaneously cleave upon treatment with TBAF and an appropriate amount of water to provide an active silicate species that promotes transmetalation. Although the chemistry of allylgermanes is well established, 19,20 the application of allyl organogermanes as substrates for the Pd-catalyzed crosscoupling with aryl halides has not been investigated.…”

New Organogermanium Substrates for Palladium-Catalyzed Cross-Coupling Reactions. Application of Organogermanes towards the Synthesis of Carbon-5 Modified Uridine Analogues

“…The amount of TBAF was found to be crucial However, attempts to induce multiple transfer of the phenyl group during fluoride-promoted couplings of (allyl) X Ph 4-X Si (x = 1 or 2) with aryl halides failed (23 and 24, Scheme 6, section 1.2.1.1). 105 It is viable that the germanium species with extra halogen ligands formed after each transmetallation cycle is rendered more reactive to efficiently transfer a second or third phenyl group from the Ge atom. Water might play multiple roles in enhancing the efficiency of the couplings as was found with organosilanes, including the formation of the reactive hydroxypalladium intermediates.…”

“…The design of the germanes 125-127 was made based on the reported transfer of the phenyl/aryl group from the moderately reactive allyl(phenyl)silanes 23 105 and aryl(2-naphthylmethyl)germanes 28 106 (see section 1.2.1.1).…”

“…However, coupling of diallyl(diphenyl)silane 24 (Scheme 6, section 1.2.1.1) with excess of 4-chloroanisole was shown to occur by transfer of only one phenyl substituent. 105 The formation of inert hexacoordinate silicate species (after the transmetallation of the first phenyl group) was assumed to be impeding a second group transfer. Moreover, coupling of the pre-synthesized tetrabutylammonium triphenyldifluorosilicate 39 ( Figure …”