Propargylethoxyamino nucleosides are disclosed having the structure 1 wherein R1 and R2 are nullH, lower alkyl, or label; B is a 7-deazapurine, purine, or pyrimidine nucleoside base; W1 is nullH or nullOH; W2 is nullOH or a moiety which renders the nucleoside incapable of forming a phosphodiester bond at the 3null-position; and W3 is nullPO4, nullP2O7, nullP3O10, phosphate analog, or nullOH. Additionaly, a primer extension method is provided employing the above propargylethoxyamino nucleosides.