Abstract: A method for preparing an oligonucleotide comprising the steps of a) providing a 3-protected compound having the formula: wherein B is a heterocyclic base R2 is H, a protected 2-hydroxyl group, F, a protected amino group, an O-alkyl group, an O-substituted alkyl, a substituted alkylamino or a C4?-O2?methylen linkage R3 is OR?3, NHR?3, NR?3R??3, a 3?-protected nucleotide or a 3?-protected oligonucleotide, R?3 is a hydroxyl protecting group, R?3, R??3 are independently an amine protecting group, b) reacting said compound with a nucleotide derivative having a 5-proctection group in the presence of a solid supported activator to give an elongated oligonucleotide with a P(III)-internucleotide bond c) optionally processing the elongated oligonucleotide with a P(III)-internucleotide bond by either or both of steps c1) and c2) in any sequence c1) capping preferably by reacting with a solid supported capping agent c2) oxidizing preferably by reacting the oligonucleotide with a solid supported oxidizing reagent d) remo

Abstract: Compounds and methods for preparing oligonucleotide analogs are provided. In preferred embodiments, the methods involve solid-phase coupling of synthons bearing either 3'-electrophillic groups and 5'-nucleophilic groups or 5'-electrophillic groups and 3'-nucleophilic groups to form neutral, achiral oligomers.