Nucleosides preparation

Repta, A. J., B. J. Rawson, R. D. Shaffer, K. B. Sloan, N. Bodor, andT. Higuchi. 1975. Rational development of a soluble prodrug of a cytotoxic nucleoside preparation and properties of arabinosylad ohrraeflie. 

Initial studies58 had indicated that 1-glycopyranosyl nucleosides prepared by the mercuri procedure are identical with those prepared by the Hilbert-Johnson method, when similar poly-O-acylglycosyl halides are employed. The applicability of the mercuri procedure to the synthesis of 1-aldopento-furanosyl nucleosides was demonstrated by the preparation of 5 -methyl-uridine (LIV). Condensation of dithyminylmercury (LI) with tri-O-benzoyl-... 

Gehrke and Patel [460] looked for optimal reaction and chromatographic conditions in the analysis of silyl derivatives of nucleosides prepared by reaction with BSTFA. They recommended performing the derivatization with a 225-fold molar excess of BSTFA at 150°C for 15 min in a closed vial and analysis on a 1 m X 4 mm ED. column packed with 4% of OV-11 on Supelcoport (100—120 mesh) with temperature programming at 5°C/ min from 140°C. 

Further examples of nucleosides prepared by Lewis acid catalyzed glycosylation are given in Table 46. 

Table 46. Nucleosides Prepared by Lewis Acid Catalyzed Glycosylation... 

The most representative examples of intramolecular free radical cyclization in carbohydrate chemistry are the syntheses of C-branched nucleosides derivatives. The key step in C-branched nucleoside preparation is the regio- and stereo-controlled formation of a new C-C bond at the branching point of the ribofuranose ring [58]. Among published reports, a temporary silicon connection is becoming a growing interest in the syntheses of C-branched nucleosides by intramolecular radical cyclization. 

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