[google470]

It is difficult to understand the reason why 0.5 eq TBAF can remove the TBDPS group completely in the refs (table 3, entry 2) below.
Could you tell me why? Thanks

Reference: Synlett, 2000, 9, 1306-1308 Link

Excerpt attached.

Mod edit: Full text link removed due to questionable legality. Replaced with referenced excerpt. Dan

[Dan]

Hint: Table 4, entry 6

[google470]

Hint: Table 4, entry 6

Thanks a lot.

So... ...it seems F-  serve as a catalyst, TBSF <--->  TBS + F-, then the TBS moiety was trapped by H2O, and F- would attack another TBSOR... ...

[Dan]

That seems reasonable. It is quite a complicated reaction in terms of mechanism - it is not exactly clear what the active desilylating species is (notice table 4, entry 1).

I guess there is a complex equilibrium:

R₃SiF + H₂O + AcO^-  R₃SiOH + HF + AcO^-  R₃SiOH + F^- + AcOH  R₃SiOAc + F^- + H₂O  and so on

[google470]

That seems reasonable. It is quite a complicated reaction in terms of mechanism - it is not exactly clear what the active desilylating species is (notice table 4, entry 1).

I guess there is a complex equilibrium:

R₃SiF + H₂O + AcO^-  R₃SiOH + HF + AcO^-  R₃SiOH + F^- + AcOH  R₃SiOAc + F^- + H₂O  and so on

so complicated...