2,6‐Diisopropoxyphenyl(dicyclohexyl)phosphine: A New Ligand for Palladium‐Catalyzed Amination Reactions of Aryl Chlorides with Potassium Hydroxide as the Base

Abstract

A new, readily available monophosphine tetrafluoroborate salt [L2·HBF 4 ] was developed for the palladium-catalyzed amination reaction of aryl chlorides in moderate to high yields with the cheap and easily available potassium hydroxide as the base. The reaction enjoys a wide scope, lower reaction temperatures, shorter reaction times, high yields, and low catalyst loading when compared to some of same amination reactions reported in the literature. Based on a kinetic study, 31 P NMR measurements, and DFT calculations, a mechanism involving a 1:1 Pd/L species is proposed.

Resorcinarenyl‐Phosphines in Suzuki–Miyaura Cross‐Coupling Reactions of Aryl Chlorides

“…For these comparative tests, the triarylphosphines tested were PPh 3 (11), (o-anisyl)diphenylphosphine (12), (2,6-dimethoxyphenyl)diphenylphosphine (13) and 2-diphenylphosphanyl-2Ј-methylbiphenyl (14; Figure 4). [35] As a result, both elementary steps, oxidative addition and reductive elimination/product decoordination, should be facilitated. [34] Under the above optimised conditions, the conversions increased in the order 11 Ͻ 12 Ͻ 13 Ͻ 2 (Table 7).…”

Negishi Coupling for Highly Selective Syntheses of Allenes via Ligand Effect and Mechanistic Study via SAESI‐MS/MS

“…From these data it is concluded that SPhos takes mono‐ligation with Pd and prevents the β‐H elimination while Gorlos‐Phos prefers bis‐ligation with Pd. Then the Gorlos‐Phos‐mono‐ligated palladium intermediate Int 2 would have the free coordination sphere required by β‐H elimination, thus, facilitating β‐H elimination during the coupling reaction to afford the β‐H elimination‐based coupling product allene 3a , as confirmed by SAESI‐MS‐MS experiment of Int 2 (eqn. 15).…”

“…After some screening, we observed the exclusive formation of ethylation product allene 2a when SPhos was used (Table , entry 4). Other mono‐phosphine ligands such as MePhos, XPhos, or Zheda‐Phos (Table , entries 5, 7, 11) also afforded a mixture of ethylation product 2a and β‐H elimination product 3a with a high selectivity while the reactions with BrettPhos or t ‐BuXPhos gave rather poor results (Table , entries 6 and 8). The loadings of SPhos and diethyl zinc could be reduced to 7.5 mol% and 2.0 equiv., respectively (Table , entry 13).…”

“…The loadings of SPhos and diethyl zinc could be reduced to 7.5 mol% and 2.0 equiv., respectively (Table , entry 13). Further screening led to the observation that with LB‐Phos or Gorlos‐Phos as the ligand, β‐H elimination‐based allene product 3a was formed with a very high selectivity (Table , entries 9 and 10). After further optimization, we found Pd(OCOCF 3 ) 2 /Gorlos‐Phos at 0 o C with 1.5 equiv.…”

Application of LB‐Phos·HBF4 in the Suzuki Coupling Reaction of 2‐Bromoalken‐3‐ols with Alkylboronic Acids

“…Because PPh 3 was ineffective both in 1,4-dioxane with K 3 PO 4 and in toluene with K 2 CO 3 ( Table 1, Entries 1 and 4), Gorlos-Phos·HBF 4 [15] ( Figure 1) was tested instead. Because PPh 3 was ineffective both in 1,4-dioxane with K 3 PO 4 and in toluene with K 2 CO 3 ( Table 1, Entries 1 and 4), Gorlos-Phos·HBF 4 [15] ( Figure 1) was tested instead.…”