In organic synthesis, appropriate use of protecting agents is very important to a synthetic strategy.Useful protecting agents must have the following properties:
- the protecting agent must selectively react with the functional group that requires protection.
- the protective group must be introduced in high yields, without side reactions.
- the protected functional groups should be stable under various reaction conditions.
- the protective group should be capable of being selectively deprotected under specific conditions that are not adverse to the integrity of the protected compound.
A list shows a wide range of protecting agents, from conventional protective groups (TMS, Boc, trityl etc.) to a new special protecting agent, 1,2-bis(chlorodimethylsilyl)ethane (which reacts only with aliphatic primary amines to generate azadisilacyclopentane derivatives) and Teoc-NT1) developed by Sodeoka and Shimizu in 2007.
Particularly, Teoc-NT is a useful protecting agent which is stable and easy to handle. It reacts rapidly with various amines, alcohols, and thiols at room temperature to give the corresponding protected compounds in high yields, respectively. The by-product nitrotriazole (NT) has low solubility in the solvent and precipitates out as a crystalline solid. As a result, NT can be removed by simple filtration. The Teoc group can be removed easily by fluoride ions under a neutral condition. Teoc-NT is applicable to the synthesis of various base-sensitive oligonucleotide derivatives.
Literature
2) Review: Protective Groups in Organic Synthesis. 3rd ed., ed. by T. W. Greene, P. G. M. Wuts, John Wiley & Sons, Inc., New York, 1999.
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