The enantiospecific synthesis of [(2′S, 3′S)-bis(hydroxymethyl)azetidin-1-yl]pyrimidine nucleosides 22, 25, and 27 was achieved via construction of the base on the 1-aminoazetidine 18 prepared from (+)-diethyl-L-tartrate, and they are the first members of a new class of nucleoside analogs in which the oxetane ring in oxetanocin-A 4 is replaced by an azetidine ring linked to a nucleic base through an