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Synthesis of DDQ involves cyanation of chloranil. J. Thiele and F. Günther first reported a 6-step preparation in 1906. [7] The substance did not receive interest until its potential as a dehydrogenation agent was discovered. A single-step chlorination from 2,3-dicyanohydroquinone was reported in 1965. [8]
The use of protective groups is pervasive but not without criticism. [103] In practical terms their use adds two steps (protection-deprotection sequence) to a synthesis, either or both of which can dramatically lower chemical yield. Crucially, added complexity impedes the use of synthetic total synthesis in drug discovery.
p-Methoxybenzyl (PMB) is used as a protecting group for alcohols in organic synthesis (4-Methoxybenzylthiol is used to protect thiols). The p -methoxybenzyl group Strong base such as powdered potassium hydroxide or sodium hydride and p -methoxybenzyl halide (chloride or bromide) [ 14 ] [ 15 ]
The absence of physical dividers between the sites occupied by individual oligonucleotides, a very limited space on the surface of the microarray (one oligonucleotide sequence occupies a square 25×25 μm) [107] and the requirement of high fidelity of oligonucleotide synthesis dictate the use of site-selective 5'-deprotection techniques.
Deprotection of Boc-protected amines can be achieved using trimethylsilyl trifluoromethanesulfonate and triethylamine or 2,6-lutidine. [7] [8] TMSOTf is also a useful reagent to replace metal-halogen bonds with a covalent M-O(SO2CF3) bond, the by-product being the highly volatile TMSCl which is easily removed.
Desulfonylation reactions are chemical reactions leading to the removal of a sulfonyl group from organic compounds.As the sulfonyl functional group is electron-withdrawing, [1] methods for cleaving the sulfur–carbon bonds of sulfones are typically reductive in nature.
Trimethylsilylacetylene is also used to synthesize diphenylacetylene derivatives in a one-pot Sonogashira coupling, in which the phenylacetylene derivative reacts with a second aryl halide after in-situ deprotection. [3] A less expensive alternative reagent is 2-methylbut-3-yn-2-ol, which after alkynylation is deprotected with base.
It is also a good test for the successful deprotection of a secondary amine. Secondary amines react with chloranil to give a brown/red/orange derivative, the colour depending on the amine. In these reactions, the amine displaces chloride from the ring of the quinone.