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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.
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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 use of triethylsilane as a carbocation scavenger in the presence of trifluoroacetic acid in dichloromethane has been shown to lead to increased yields, decreased reaction times, simple work-up and improved selectivity for the deprotection of t-butyl ester and t-butoxycarbonyl sites in protected amino-acids and peptides in the presence of ...
Trimethylsilyl trifluoromethanesulfonate has a variety of other specialized uses. It has been used to install tert-alkyl groups on phosphine (R = alkyl): [6] PH 3 + R 3 C–OAc + Me 3 SiOTf → [(R 3 C) 2 PH 2]OTf. Deprotection of Boc-protected amines can be achieved using trimethylsilyl trifluoromethanesulfonate and triethylamine or 2,6 ...
The use of Fmoc as a temporary protecting group for amine at the N-terminus in solid phase synthesis is very widespread for Fmoc/tBu approach, because its removal with piperidine does not disturb the acid-labile linker between the peptide and the resin. [7]