Chemoselective Deprotection of Aryl tert-Butyldimethylsilyl Ethers Promoted by Phosphates

Abstract

A facile protocol to the chemoselective deprotection of aryl t-butyldimethylsilyl (TBDMS) ethers using Na₃PO₄ · 12H₂O as promoter is described. From aryl TBDMS ethers to the corresponding phenols, the TBDMS group could be cleaved in the presence of 0.5 equivalent of Na₃PO₄ · 12H₂O in dimethylformamide at room temperature with good to excellent yields in the presence of other common protecting and functional groups. K₃PO₄ · 3H₂O was also found to be useful for the selective deprotection reaction. This is, to our knowledge, the first report on chemoselective deprotection of aryl TBDMS ethers using phosphates.

GRAPHICAL ABSTRACT

Keywords:

• 4-Desmethyllepipodophyllotoxin
• K₃PO₄ · 3 H₂O
• Na₃PO₄ · 12 H₂O
• selective deprotection
• t-butyldimethylsilyl (TBDMS)

ACKNOWLEDGMENT

This work was supported by international cooperation grants from Henan Province (104300510062).

Notes

^a Reactions were conducted under 0.5 equiv. Na₃PO₄ · 12H₂O in different solvents (2 ml) at room temperature (0.5-mmol scale).

^b Isolated yield.

^c  NR, no reaction.

^a Reactions were conducted under 0.5 equiv. Na₃PO₄ · 12H₂O in DMF at room temperature (0.5-mmol scale, 2 ml DMF).

^b Isolated yield.

^c Reactions were conducted at 100 °C.

^d NR, no reaction.

^a Reactions were conducted under 0.5 equiv. Na₃PO₄ · 12H₂O in DMF at room temperature (0.5-mmol scale, 2 ml DMF).

^b Isolated yield.

^a Reactions were conducted under 0.5 equiv. K₃PO₄ · 3H₂O in DMF–H₂O (10:1, v/v) at room temperature (0.5-mmol scale, 2 ml DMF).

^b Isolated yield.