Fig. 8

a Selective transformation of Ph₃P(O) to sodium benzo[b]phosphindol-5-ide 4. b Reaction conditions and monitored by ³¹P NMR: (a) sodium H-benzo[b]phosphindol-5-olate 3 was generated in situ from Ph₃P(O) (0.9 mmol) and PhNa (1.0 mmol); (b) SD (2.5 mmol) was then added and stirred for 2 h; (c) n-BuBr (2.0 mmol) was added to the mixture and stirred for 1 h. c One-pot conversion of Ph₃P(O) to phosphle 4′. Isolated yield. ^a0.4 mmol of BrC₄H₈Br was added. ^bThe product was oxidized by H₂O₂ for easy isolation.