Other Methods of Nucleoside Synthesis

Comparison with Other Methods of Nucleoside Synthesis 

In addition to the Hilbert-Johnson reaction, the so-called mercuri process,37 and, less frequently, the cyclization procedure of Shaw et a/.,53 64 have been used for the synthesis of nucleosides and their derivatives. l-Peracylglycosyl-4-alkoxy-2(l//)-pyrimidinones, the intermediates of the Hilbert-Johnson reaction, can be, in principle, prepared 56,56 also by the mercuri process, namely by reaction of 4-ethoxy-2(lZ/)-pyrimidinone chloromercuri salt with the corresponding halogenoses, but this method is of less importance because of the contamination of iV-l-glycosyl derivatives with the 0-2 isomers, namely, with 2-peracylglycosyloxy-4-alkoxypyrimidines. The advantageous features of the mercuri process in comparison with the Hilbert-Johnson reaction might be formulated as follows. 

Hayatsu, and Y. Tomita, Chem. Pharm. Bull. (Tokyo) 11, 1068 (1963). 

The products of the mercuri process in most cases possess a C-V-C-2 -trans system in accordance to the Baker trans rule61-64 and are sterically more uniform than the Hilbert-Johnson products. On the other hand, certain anomers inaccessible by the mercuri process may be obtained under certain conditions (solvent) by the Hilbert-Johnson reaction as a mixture with the other anomer chromatographic methods have been worked out to separate these mixtures almost quantitatively into the individual anomers (cf. Section X). The Hilbert-Johnson reaction intermediates may be converted into nucleosides of both types, of the uridine type as well as of the cytidine type (cf. Section V), whereas conversion of the mercuri process of the uridine type into the cytidine type is somewhat tedious. On the whole, the Hilbert-Johnson reaction represents a suitable complementary method to the mercuri process. 

Ciba Found. Symp. Chem. Biol. Purines, p. 120 (1957). 

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XI. Comparison with Other Methods of Nucleoside Synthesis. 137... 

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