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The classical protecting groups for alcohols are esters, deprotected by nucleophiles; triorganosilyl ethers, deprotected by acids and fluoride ions; and (hemi)acetals, deprotected by weak acids. In rarer cases, a carbon ether might be used.
The group is even more resistant to acid hydrolysis than the bulky TIPS. However, in the presence of a fluoride source such as TBAF or TAS-F, TIPS groups are more stable than TBDPS groups. The TBDPS group is of similar stability to the TBDMS group and is more stable in the presence of fluoride than all other simple alkyl silyl ethers. [5]
tert-Butyloxycarbonyl protecting group. The tert-butyloxycarbonyl protecting group or tert-butoxycarbonyl protecting group [1] (BOC group) is an acid-labile protecting group used in organic synthesis. The BOC group can be added to amines under aqueous conditions using di-tert-butyl dicarbonate in the presence of a base such as sodium hydroxide:
Silyl ethers are a group of chemical compounds which contain a silicon atom covalently bonded to an alkoxy group. The general structure is R 1 R 2 R 3 Si−O−R 4 where R 4 is an alkyl group or an aryl group. Silyl ethers are usually used as protecting groups for alcohols in organic synthesis.
Benzyl is commonly used in organic synthesis as a robust protecting group for alcohols and carboxylic acids. Treatment of alcohol with a strong base such as powdered potassium hydroxide or sodium hydride and benzyl halide (BnCl or BnBr) [9] [10]
The word "butyl" is derived from butyric acid, a four-carbon carboxylic acid found in rancid butter. [1] The name "butyric acid" comes from Latin butyrum, butter. Subsequent preferred IUPAC names for alkyl radicals in the series are simply named from the Greek number that indicates the number of carbon atoms in the group: pentyl, hexyl, heptyl ...
The protection mechanism begins with the base deprotonating the alcohol group. Next, the deprotonated alcohol group attacks the silyl atom of the silyl halide compound. The halide acts as a leaving group and ends up in solution. A workup step follows to remove any excess base within the solution. The overall reaction scheme is as follows:
This is useful because alcohols are poor leaving groups in S N 2 reactions, in contrast to the tosylate group. It is the transformation of alkyl alcohols to alkyl tosylates that allows an S N 2 reaction to occur in the presence of a good nucleophile. A tosyl group can function as a protecting group in organic synthesis. Alcohols can be ...