No abstract

General MethodsAll air-and moisture-sensitive manipulations were carried out with standard Schlenk techniques under nitrogen or in a glove box under nitrogen. 1 H, 13 C and 31 P NMR spectra were recorded on a Varian instrument (400/600 MHz, 100/150 MHz and 162 MHz, respectively). 1 H, 13 C NMR chemical shifts are reported vs tetramethylsilane signal or residual protio solvent signals.Hexane, Toluene, and dichloroethane were distilled over CaH2 under nitrogen. THF, Et2O were distilled over sodium benzophenone ketyl under nitrogen.Unsaturated sulfonamide 1 1 , diarylphosphine 2 2 and the catalyst PCP-PdOAc 3 were synthesized following the literature procedures. Other chemicals and solvents were purchased from commercial company and used as received. Experimental Details and Characterization Data General procedure A: Asymmetric Addition of Diarylphosphines to α,β-Unsaturated SulfonamidesA flame-dried reaction tube was charged with 1 (0.22 mmol, 1.1 equiv), Pd catalyst (2.7 mg, 0.004 mmol, 2 mol%). After purging with nitrogen for three times, toluene (3.0 mL) was added. The reaction mixture was stirred at 40 °C for 15 min, followed by addition of diphenylphosphine (0.20 mmol, 1.0 equiv). After being stirred at 40 °C for 24 h, the mixture was quenched by sulfur (9.6 mg, 0.30 mmol, 1.5 equiv.) and stirred at 40 °C for 8 h. The mixture was filtered through a short plug of silica gel with CH2Cl2, concentrated under vacuum. The residue was purified through flash chromatography on silica gel with hexane/ethyl acetate = 5:1 to afford the desired product 3 as the white solid.

A method that involved an asymmetric 1,4‐addition of secondary phosphines to β‐(2‐pyridyl)‐substituted enones by using a tridentate pincer palladium catalyst is developed.