Fig. 3: Reaction of triphenylphosphine oxide with sodium.

a Triphenylphosphine oxide 1 rapidly reacted with sodium at 25 °C. Reaction conditions: 0.5 mmol Ph3P(O) was dissolved in 3 mL THF, and 2.5 mmol metallic Na was added at 25 °C. b The reaction mixture was stirred for 1 h, 2 h and overnight and monitored by 31P NMR, respectively.