Group transfer reagents

Coenzymes serve as recyclable shuttles—or group transfer reagents—that transport many substrates from their point of generation to their point of utilization. Association with the coenzyme also stabilizes substrates such as hydrogen atoms or hydride ions that are unstable in the aqueous environment of the cell. Other chemical moieties transported by coenzymes include methyl groups (folates), acyl groups (coenzyme A), and oligosaccharides (dolichol). 

Monomercurated A/-Protected Pyrroles as Pyrrolyl Group Transfer Reagents... 

An approach to the problem is summarized in eq. (3). Aldehydes are subject to catalytic olefination when certain aliphatic diazoalkanes are used as alkylidene group transfer reagents phosphines are necessary to carry off the 0x0 group. 

Similarly, p3ridine addition to aldehydes is also promoted by TMSOTf in a three-component reaction to form [l-(trimethyl-siloxy)alkyl]p3Tidinium salts (eq 62), which may act as group transfer reagents or as precursors for the analogous phosphonium... 

Zdilla MJ, Abu-Omar MM (2006) Mechanism of catalytic aziridination with manganese corrole the often postulated high-valent Mn(V) imido is not the group transfer reagent. J Am Chem Soc 128(51) 16971-16979... 

A-Acyl-4-pyridones can serve as useful acyl group transfer reagents for the esterification of alcohols in >80% yields.Two notable points about these reagents are their effectiveness in the preparation of formate esters (c/. ref. 157), and their much greater rate of reaction with primary alcohols, (c/. ref. 147). Thioesters and amides can also be prepared from such pyridones by reaction with thiols or amines, respectively. Other useful reagents for the direct formation of esters from carboxylic acids and alcohols are 2-fluoropyridinium salts in the presence of caesium fluorideand certain benzoisothiazole derivatives. Primary alcohols can be esterified with 2,2 -bipyridyl-6-yl carboxylates and CsF. Selective esterification of a primary alcohol in the presence of a secondary alcohol can be achieved in acceptable yields with this reagent (c/. ref. 144). 

Dimethylaluminium methylselenolate reacts with O-alkyl esters to provide methyl selenol esters the latter are good acyl group transfer reagents. ... 

Thioesters and Related Compounds.—A new general route to thio- and seleno-esters employs the versatile push-pull acetylene (157) as an acyl group transfer reagent. Reaction with carboxylic acids (which may contain unprotected OH, NH2, or SH groups) affords enol esters (158) which give thio- or seleno-esters on... 

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