Phosphoric imidazolides

Besides CDI, other azolides such as A N -oxalyldiimidazole, AyST-carbonyldi-1,2,4-triazole, MN -oxalyldi-1,2,4-triazole, and phosphorous and phosphoric imidazolides have been used in the synthesis of peptide bonds, as displayed in Table 5-4. 

In the case of arabinosyladenine-5 -phosphoric imidazolide, a reaction with the 2 -OH of the sugar moiety was observed ... 

Another cyclization of 3 -adenylic acid (3 -AMP) to 2, 3 -cyclic adenylic acid (2, 3 -cAMP) took place by condensation with carbiminodiimidazole (or iV-cyanoimidazole) in aqueous or anhydrous medium. It is supposed that the reaction of 3 -AMP probably proceeds via a phosphoric imidazolide [9]... 

The dialkyl(l-methylacetonyl)phosphates, which were easily hydrolyzed, are obtained in higher than 90% yields. Such reactions can also be carried out by making the phosphoric imidazolide in situ from the di(l,2-dimethylethylene)pyrophosphate and imidazole.[10]... 

The phosphoric imidazolide was prepared either from the corresponding oligonucleotide and CDI or from the oligonucleotide, imidazole, dipyridyldisulfide, and triphe-nylphosphine. Both procedures led to yields greater than 90%. 91]... 

The capped leader sequence of the brome mosaic virus mRNA, an oligonucleotide 5 triphosphate, has been synthesized analogously by reaction of an oligoribonucleotide 5 -phosphoric imidazolide. 951... 

The reaction of adenosine 5 -phosphoric imidazolide with adenosine analogues on a polyuridylic acid template is discussed in reference [158]. Another polymerization of oligoadenylates (pA)4 and (pA)6 on a polyuridylic acid template in an aqueous system... 

Condensation of the 5 -phosphoric imidazolide of adenosine (ImpA) with itself and P yP -diadenosine 5, 5 -phyrophosphate (AppA) in water in the presence of Na -mont-morillonite clay leads mainly to 3, 5 -linked oligomers. These results are discussed in the context of the potential importance of mineral catalysts to the formation of RNA on the... 

Condensations of adenosine 5 -phosphoric imidazolide with glycolic or lactic acid in aqueous solution with divalent metal ions as catalysts to give glycolyl adenylate or lactyl adenylate are described in reference [175]. 

Acceleration of the Template- and Metal-Directed Polycondensation of Nucleoside-5 -phosphoric Imidazolides by Acylation... 

In this procedure a diacylglyceryl phosphate is first converted with CDI into a reactive phosphoric imidazolide, which is then treated with a labeled alcohol to give a labeled phosphoric acid diester 123... 

The reaction is carried out under mild neutral conditions (dioxane, room temperature, 20 h) without the need for a base such as triethylamine, as would be required if the chloridate were used instead of the imidazolide. Furthermore, yields of phosphates are higher by using the phosphoric imidazolide.[ 1873... 

Spin-labeled phosphoramidates are synthesized analogously by the reaction of phosphoric imidazolides with primary or secondary amines[189] or amino acid esters.11883... 

The inductive effect of the imidazole substituents on the transphosphorylation of alcohols and amines with the following spin-labeled phosphoric imidazolides is discussed in reference [190]. 

The effect upon the transphosphorylation reaction with alcohols and amines of electron-releasing (CH3) and electron-withdrawing (Cl, N02) groups in the benzene ring of phosphoric imidazolides has been studied as well.[191]... 

Recently a very mild method was discovered for the synthesis of dinucleoside fluorophosphates in the conversion of a dinucleoside phosphite with iV V -oxalyldiimi-dazole into the corresponding phosphoric imidazolide, which is then treated with acyl fluoride [204] <202]... 

Imidazolesulfonic acid reacts with phosphinic and phosphoric imidazolides to give mixed anhydrides of the following type 1501... 

With the phosphoric imidazolides D, E, and F, dehydration of the aldoximes can also be achieved (dioxane, room temperature, several hours). With diphenylimidazole-1-phosphonate (D) and phenyldiimidazole-l,l -phosphinate (E) the yields of nitriles are always higher than with (C6H50)2P(0)C1 and C6H50P(0)C12 however, with phosphoryl triimidazole (F) the yields are a little lower than with POCl3.[9] Spin-labeled phosphoric imidazolides of this type are also used for the dehydration of aldoximes.1103... 

Kadokura, M., Wada, T., Urashima, C., and Sekine, M. (1997). Efficient synthesis of g-methyl-capped guanosine. V-mphosphate as a SLtcrminal unique structure of U6 RNA via a new triphosphate bond formation involving activation of methyl phosphor-imidazolidate using ZnCl2 as a catalyst in DMF under anhydrous conditions. Tetrahedron Lett. 38, 8359-8362. 

The chemical synthesis of mono-, di-, tri-, and tetraphosphates usually starts with unprotected nucleosides to produce posphoamidates at first. The monophosphate may be treated either with morpholine and DCC to afford the phosphoro-morpholidate or with carbonyl bis(imidazole) to yield the phosphor imidazolidate. A third method uses diphenylphosphorochloridate to give a pyrophosphate triester (Scheme 8.5.10). All three intermediates react with orthophosphate, diphosphate, or ATP to yield di-, tri-, or tetraphosphates, respectively. 

---