Convergent synthesis of phosphorodiamidate morpholino oligonucleotides (PMOs) by the H-phosphonate approach.

Phosphorodiamidate morpholino oligonucleotides (PMOs) are a promising type of antisense oligonucleotides, but their challenging synthesis makes them difficult to access. This research presents an efficient synthetic approach for PMOs using the H-phosphonate approach. The use of phosphonium-type condensing reagents significantly reduced coupling times compared with the current synthetic approach.

Properties of 5- and/or 2-modified 2'-O-cyanoethyl uridine residue: 2'-O-cyanoethyl-5-propynyl-2-thiouridine as an efficient duplex stabilizing component.

We systematically synthesized eight types of 5- and/or 2-modified uridine derivatives and evaluated their effect on duplex stability. The incorporation of 2'-O-cyanoethyl-2-thio-5-propynyluridine (p(5)s(2)UOCE) into RNA was significantly effective for stabilization of RNA/RNA (+8.5 °C) and DNA/RNA (+10.

Prediction of the stability of modified RNA duplexes based on deformability analysis: oligoribonucleotide derivatives modified with 2'-O-cyanoethyl-5-propynyl-2-thiouridine as a promising component.

We describe a method to predict the stability of a modified RNA duplex. Ten unique modified RNA duplexes showed a linear relationship between the calculated and experimentally determined duplex stabilities.

Total syntheses of (+)-1893B and its three diastereomers and evaluation of their biological activities.

The total syntheses of natural (+)-1893B (2) and three other diastereomers 14, 18, and 21 were accomplished. Starting from the sequential metathesis product 5 prepared in turn from a 7-oxanorbornene derivative (+)-4, 2 was synthesized by means of an epoxy-ring opening of 9a with trimethylsilylacetylide followed by Wacker-type oxidation of the resulting alkyne 10 for the construction of the gamma-lactone moiety. By applying the same synthetic sequence, three additional diastereomers of 2, 14, 18, and 21 were also synthesized.