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As the name suggests, a non-nucleophilic base is a sterically hindered organic base that is a poor nucleophile.Normal bases are also nucleophiles, but often chemists seek the proton-removing ability of a base without any other functions.
Pages in category "Non-nucleophilic bases" The following 26 pages are in this category, out of 26 total. This list may not reflect recent changes. ...
It is used as a non-nucleophilic base, being comparable to LiHMDS in terms of steric hindrance. Synthesis It is ...
Tetramethylguanidine is mainly used as a strong, non-nucleophilic base for alkylations, often as a substitute for the more expensive DBU and DBN. [3] Since it is highly water-soluble, it is easily removed from mixtures in organic solvents. It is also used as a base-catalyst in the production of polyurethane. [4]
Mutation of the active site nucleophile to a non-nucleophilic amino acid prevents the formation of a covalent intermediate. An activated glycosyl donor with a good anomeric-leaving group (often a fluorine) is required. The leaving group is displaced by an alcohol of the acceptor sugar aided by the active site general base amino acid of the enzyme.
Glycosylation is an important parameter in the optimization of many glycoprotein-based drugs such as monoclonal antibodies. [6] Glycosylation also underpins the ABO blood group system. It is the presence or absence of glycosyltransferases which dictates which blood group antigens are presented and hence what antibody specificities are exhibited.
BEMP and P4-t-Bu|t-Bu-P 4 have attracted attention because they are low-nucleophilic, which precludes their participating in competing reactions. Being non-ionic ("charge-neutral"), they are soluble in nonpolar solvents. Protonation takes place at a doubly bonded nitrogen atom. [3]
DNA and RNA also contain other (non-primary) bases that have been modified after the nucleic acid chain has been formed. In DNA, the most common modified base is 5-methylcytosine (m 5 C). In RNA, there are many modified bases, including those contained in the nucleosides pseudouridine (Ψ), dihydrouridine (D), inosine (I), and 7-methylguanosine ...