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A tricoordinate phosphorus, used on account of the high reactivity, is tagged with a cyanoethyl protecting group on a free oxygen. After the coupling step follows an oxidation to phosphate, whereby the protecting group stays attached. Free OH-groups, which did not react in the coupling step, are acetylated in an intermediate step.
The ease of installation of the protecting group follows the order: 1 o > 2 o > 3 o, allowing the least hindered hydroxyl group to be protected in the presence of more hindered hydroxyls. [ 4 ] Protection of equatorial hydroxyl groups can be achieved over axial hydroxyl groups by the use of a cationic silyl species generated by tert ...
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.
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:
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 ...
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]
Hemiacetals form in the reaction between alcohols and aldehydes or ketones. Using an acid catalyst, the reaction proceeds via nucleophilic attack of the carbonyl group by the alcohol. [4] A subsequent nucleophilic attack of the hemiacetal by the alcohol results in an acetal. [2] Solutions of simple aldehydes in alcohols mainly consist of the ...