The invention relates to a method for synthesizing five-membered
carbocyclic nucleoside, comprising the following steps of: 1) synthesizing a compound 26 in the reaction equation 1, and oxidizing the compound 26 into a dicarbonyl compound 34 by the use of a TEMPO-NaClO
system; 2) carrying out selective protection on
ketone carbonyl in the compound 34 to generate a compound 35; 3) reducing
ketone carbonyl in the compound 35 into a compound 36 with a terminal containing a
double bond; 4) performing an
addition reaction between the compound 36 and
hydrogen bromide by anti-Markovnikov's rule to obtain a
bromide 37; and 5) carrying out
lithium halogen exchange on the compound 37 to generate
nucleophilic addition cyclization within the molecules so as to obtain a compound 38, namely five-membered ring carbasugars; and performing a routine reaction to obtain the five-membered
carbocyclic nucleoside. By the adoption of the method provided by the invention, the yield of the five-membered ring carbasugars is greatly raised, and simultaneously usage frequency of extreme low temperature reaction is minimized. All the raw materials used are cheap and easily available.