A-Pseudouridine

The proton signals of uridine (36) dissolved in deuterium oxide are well separated at 220 MHz, and a complete analysis and simulation of the spectrum by means of the LAOCOON II computer program (see Section V, p. 74) has been reported.107 It was concluded from the temperature-independence of the coupling constants and chemical shifts of the D-ribofuranoid moieties of uridine, /3-pseudouridine (40), and a-pseudouridine (41), that each of these compounds... 

Cyclic Trimer Configuration. The a-cytidine [ACYTID] crystal structure contains two cyclic trimer configurations (Fig. 17.32). In one, N(H)H is engaged in a three-center bond, the other is a homodromic cycle stabilized by a- and w-cooperativity. A comparable situation is found in the crystal structure of a-pseudouridine monohydrate [APSURD] (Fig. 17.13). The glycosyl link is to uracil C(6) instead of N(l), and therefore the N(1)H group is free to donate a hydrogen bond in a homodromic cycle. 

The crystal structure of a-pseudouridine monohydrate [APSURD] (Fig. 17.13) has a particularly strong hydrogen-bond system consisting of a three-bond homo-dromic cycle stabilized by it- and o-cooperativity (see Fig. 17.9b) linked to an infinite chain through the water molecule. 

Sodium ferf-butoxide in N,N-dimethylformamide at KXP was found to be very effective in promoting intramolecular displacements408 and 2,5 -anhydrothymidine was obtained directly from 5 -0-(methyl-sulfonyl)thymidine with these reagents. The same conditions have also been used to synthesize the anhydronucleosides 121 and 122 from a pseudouridine derivative408 and from a D-ribosyl derivative of 2,4-quinazolinedione.410 The same reagents with 3 -0-p-tolylsulfonyl-uridine gave mainly 1 -(2,3 -anhydro-y3-D-xylofuranosyl)uracil.408... 

Fig. 17 (a) Pseudouridine, (b) Pseudouridine residue from UDG-inhibitor cocrystal... 

Another interesting feature of the active site is evident in the structure of UDG cocrystalhzed with a pseudouridine-containing ohgo-DNA inhibitor (Fig. 

In acid or basic media, pseudouridine (3) equilibrates to a mixture of its a-anomer, named a-pseudouridine (890) (Scheme 252) together with the a- and jS-pyranoside forms (60JBC1488 66MI1). The conformation (70JA4950 71JA1765 73MI1) and crystal structure (70JA4950) of a-pseudouridine (890) have also been studied. 

C9H12N2O6 244.204 Produced by acid treatment of Pseudouridine C. Mp 218-219°. The name a-Pseudouridine is confusing. 

The anomeric analogues (67) of the nucleoside moiety of the polyoxins have been prepared. C.d. was used to show the stereochemistry of the products. The synthesis shown in Scheme 8 has been used to prepare the 4 -C-allyl nucleoside (68), and related analogues of nucleocidin were also synthesized. A pseudouridine derived from a 5-C-methyl-6-deoxy-n6o-hexose is mentioned in the next section. 

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