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N-Terminal Deprotection

Standard Removal of Boc Protecting Group

  • Suspend the resin in 50% (v/v) TFA/dichloromethane (DCM), using 1 mL of TFA/DCM per gram of resin.
  • Shake the resin at room temperature for 3 minutes.
  • Filter the resin.
  • Add a second portion of 50% TFA/DCM.
  • Shake the resin at room temperature for 5 minutes.
  • Wash the resin three times with DCM (1 mL/gm resin).
  • Wash the resin three times with 5% (v/v) diisopropylethylamine (DIPEA)/DCM) (1 mL/gm resin) to remove TFA. 

Standard Removal of Fmoc Protecting Group

  • Place the resin in a round bottom flask and add 20% (v/v) piperidine in DMF (approximately 10 mL/gm resin). 
  • Shake the mixture at room temperature for 2 minutes.
  • Filter the resin.
  • Add a second portion of 20% piperidine in DMF.
  • Shake the mixture at room temperature for 5 minutes.
  • Filter the resin and wash it with several portions of DMF.

 

Removal of Fmoc Protecting Group with DBU

DBU-piperidine Deprotection Reagent

Dissolve 2.0 g of DBU and 2.0 mL of piperidine in DMF or NMP to make 100 mL.

DBU Deprotection Procedure

  • Place the resin in a round bottom flask and add 20% (v/v) piperidine in DMF (approximately 10 mL/gm resin). 
  • Shake the mixture at room temperature for 2 minutes.
  • Filter the resin.
  • Add a second portion of the deprotection reagent (approximately 10 mL/gm resin).
  • Shake the mixture at room temperature for 5 minutes.
  • Filter the resin and wash it with several portions of DMF.