Palladium-catalyzed phosphorylation of arylsulfonium salts with P(O)H compounds via C–S bond cleavage

Herein we report a novel palladium-catalyzed phosphorylation of arylsulfonium salts with P(O)H compounds via C–S bond cleavage under mild conditions. The protocol provides a pragmatic strategy applicable to the synthesis of diverse arylphosphonates.


General information:
All the palladium-catalyzed phosphonation reactions were carried out in oven-dried glassware sealed with rubber septa under N2 atmosphere. Column chromatography was performed on silica gel 200 -300 mesh. All the compounds were known and characterized by 1 H NMR, 13 C NMR and 31 P NMR with 400 MHz Bruker AVANCE spectrometers (400 MHz, 100 MHz and 162 MHz, respectively). Chemical shifts are reported relative to tetramethylsilane (TMS, δ 0.0 ppm) for 1 H NMR and CDCl3 (δ 77.0 ppm) for 13 C NMR.

Materials:
Unless otherwise noted, all reagents were purchased energy chemistry, Ouhe and J&K and used without further purification. Solvents were purified according to standard operation procedure. The arylsulfonium salts 1r to 1q were prepared in accordance with references. [1] 2. General procedures for the synthesis of arylsulfonium triflates 1r-w [1][2] .
The crude product was purified by crystallization from dichloromethane/diethyl ether system to give the desired alkyl(diaryl)sulfonium triflates 1t-w.
Note that the H-phosphonate diester 2a in a liquid form was added to the reaction tube by syringe after being added in the solvent. The reaction was heated at 80 º C with stirring for 16 h, then cooled to room temperature. After completion of the reaction, the reaction was quenched with water and extracted with EA (25 ml × 3). The organic layers were combined and washed with brine twice. It was dried over anhydrous Na2SO4 and solvent was then removed in vacuo to leave a crude mixture, which is purified by silica gel column chromatography to afford the pure desired product 3a.

One-pot phosphonation of aryl sulfide.
A 10 mL of a flame-dried seal tube equipped with a magnetic bar was charged with methyl phenyl sulfide ( The reaction flask was degassed three times with nitrogen and dry iPrOH (2.0 mL) was added using a syringe. Note that the H-phosphonate diester 2a in a liquid form was added to the reaction tube by syringe after being added in the solvent. The reaction was heated at 80 º C with stirring for 16 h, then cooled to room temperature.
After completion of the reaction, the reaction was quenched with water and extracted with EA (25 ml × 3). The organic layers were combined and washed with brine twice.
It was dried over anhydrous Na2SO4 and solvent was then removed in vacuo to leave a crude mixture, which is purified by silica gel column chromatography to afford the pure desired product 3a.