Abstract The synthesis is described of the first members of a new class of nucleoside analogues in which the tetrahydrofuran ring is replaced by a pyrrolidine ring linked to the base through an NN bond: the pyrrolidinyl analogues of 2′, 3′-dideoxycytidine (10), uridine (8), and thymidine (9) were prepared via construction of the base on a 1- aminopyrrolidine (15).