Nucleoside analog phosphoramidites are provided in which the 3'-hydroxyl group is protected with an 2-N-amidoethyl group. The 2-N-amidoethyl protected nucleoside analogs are useful in the synthesis of a wide variety of oligonucleotide analogs. Coupling yields with the protected phosphoramidites in solution or solid phase oligonucleotide analog synthesis are high and the 2-N-amidoethyl group can be removed easily under standard conditions.