Palladium‐Catalyzed Cross‐Coupling Reactions of Organogold(I) Reagents with Organic Electrophiles

Abstract

The palladium-catalyzed cross-coupling reaction of organogold(I) reagents (alkyl, alkenyl, aryl, and alkynyl) with organic electrophiles, such as aryl and alkenyl halides, aryl triflates, benzyl bromide, and benzoyl chloride is reported. The reaction takes place, under palladium catalysis, at room temperature with short reaction times to give the corresponding cross-coupling products in high yields.

Organogold(I) Phosphanes in Palladium‐Catalyzed Cross‐Coupling Reactions in Aqueous Media

“…Interestingly, the addition of PdCl 2 (PPh 3 ) 2 (5 mol‐%) to a homogeneous H 2 O/THF (9 mL, 2:1) solution of previously isolated PhAuPPh 3 (110 mol‐%) and 4‐iodotoluene (100 mol‐%), afforded the cross‐coupling product 3a in 91 % yield in 1 h at room temperature (Table 1, Entry 1). This result is identical to that obtained with pure THF as solvent (Table 1, Entry 2)11a and shows the high stability of the organogold(I) phosphane in aqueous media (protodeauration was not detected). It is interesting to note that is not necessary to use degassed solvents and that the reaction can be carried out with water taken directly from the tap.…”

“…Interestingly, a similar result was also reported by Gagné for the palladium‐catalyzed cross‐coupling reactions between isolated vinyl‐ or arylgold(I) reagents and tolyl triflate 19. In our previous work,11a we reported that when the organogold reagent was generated in situ, the cross‐coupling reaction between 1a and 9 produced 10a in 93 % yield, which suggests that the lithium chloride generated during the formation of the organogold(I) phosphane could play a crucial role in the coupling. The LiCl effect in palladium‐catalyzed cross‐coupling reactions was discovered by Stille when using organotin reagents,20 and can be attributed to stabilization of the palladium species after the oxidative addition.…”

“…General Procedure for the Preparation of Organogold Compounds: 11a A 25 mL round‐bottomed flask containing a stirrer bar was charged with Ph 3 PAuCl (75 mg, 0.152 mmol) and a positive argon pressure was established. Dry THF (3 mL) was added, and the resulting solution was cooled to –20 °C.…”

Bimetallic Catalysis using Transition and Group 11 Metals: An Emerging Tool for CC Coupling and Other Reactions

“…[102] More recently, Sarandeses and co-workers obtained related results. [103,104] In both cases the gold(I) de- Blum and co-workers have modified this reaction towards the very good yield synthesis of functionalized butenolides and isocoumarins, using both metals in catalytic amounts. [105] The authors propose the formation of the allyl oxonium intermediate generated by Au-catalyzed cyclization rearrangement of the starting allenoate.…”

Pd(0)/Au(i) redox incompatibilities as revealed by Pd-catalyzed homo-coupling of arylgold(i)-complexes

“…Reports of at least partial success in interfacing Au- and Pd catalysis in this manner have been published by Blum, 10 Hashmi, 11 Sarkar, 12 and Sestelo. 13 In particular, Blum has reported an impressive example of bimetallic catalysis wherein a gold-vinyl intermediate obtained from an allene activation reaction could be intercepted by an in situ formed palladium π-allyl species to perform a vinyl-allyl coupling that was catalytic in both gold and palladium. 14 We report herein that undesirable redox reactions between Pd(0) and Au( i ) can interfere with the normal operation of several putative catalytic cycles that could couple the reactivity of Au and Pd.…”