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dC (Bz) Et-Phosphoramidite

dC (Bz) Et-Phosphoramidite

Phosphoramidite used to incorporate a deoxycytidine into an oligonucleotide, with an ethylated backbone.

Key features

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  • Useful for creating nuclease resistant ethyl phosphotriester linkage.
  • Through incorporation into liposomes, effective in the inhibition of protein expression and cell growth in therapeutic applications.
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Product information

The UltraMILD set of methyl phosphoramidites, in conjunction with UltraMILD deprotection conditions, can be used to prepare the interesting, nuclease resistant methyl phosphotriester linkage. These have potential therapeutic applications.

We also produce a range of ethyl phosphoramidites with classical nucleobase protection. Nuclease resistant P-ethoxy oligonucleotides (a hydrophobic analogue of phosphodiesters) have been shown, through incorporation into liposomes, to be effective in the inhibition of protein expression and cell growth in therapeutic applications.(1) The neutral charge and slight lipophilic character appears to improve the delivery of the oligonucleotide into a cell.


  1. (a) Cellular pharmacology of P-ethoxy antisense oligonucleotides targeted to Bcl-2 in a follicular lymphoma cell line, Y. Gutiérrez-Puente, A.M. Tari, R.J. Ford, R. Tamez-Guerra, R. Mercado-Hernandez, M. Santoyo-Stephano, and G. Lopez-Berestein, Leuk. Lymphoma., 44, 1979-85, 2003. (b) Safety, pharmacokinetics, and tissue distribution of liposomal P-ethoxy antisense oligonucleotides targeted to Bcl-2, Y. Gutiérrez-Puente, A.M. Tari, C. Stephens, M. Rosenblum, R.T. Guerra, G. Lopez-Berestein, J. Pharmacol. Exp. Ther., 291, 865-9, 1999.

Applicable Products

LK2516 dT-Ethyl Phosphoramidite
LK2517 iBu-dG-Ethyl Phosphoramidite
LK2518 Bz-dA-Ethyl Phosphoramidite
LK2519 Bz-dC-Ethyl Phosphoramidite

Physical & Dilution Data

Dilution volumes (in ml) are for 0.1M solutions in dry acetonitrile (LK4050). Adjust accordingly for other concentrations. For µmol pack sizes, products should be diluted as 100µmol/ml to achieve 0.1M, regardless of molecular weight.


Mol. Formula

Mol. Wt.

Unit Wt.




LK2516 C39H50N3O8P 719.82 304.20 3.47 6.95 13.89
LK2517 C43H55N6O8P 814.92 329.21 3.07 6.14 12.27
LK2518 C46H53N6O7P 832.94 313.21 3.00 6.00 12.01
LK2519 C45H53N4O8P 808.91 289.18 3.09 6.18 12.36


A coupling time of 6min (360s) is recommended.

Cleavage & Deprotection

Assuming your strategy is to retain the ethyl groups, carry out deprotections at room temperature. Heating the oligos during deprotection will lead to loss of OEt from the phosphate backbone.

LK2516 & LK2518 - Use ammonium hydroxide solution overnight at room temperature.

LK2517 - Use ammonium hydroxide solution at room temperature for 48h. Overnight deprotection does not completely remove the iBu nucleobase protection (~13% remains).

LK2519 - Use ammonium hydroxide solution overnight at room temperature. Note that deprotection with AMA will lead to transamination.

After deprotection remove the deprotection solution by G25. Do not heat the sample to remove deprotection reagents.

Storage & Stability

All phosphoramidites are stored refrigerated at a maximum of 2-8°C. Stability in solution is 2-3 days.

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