Platform for the synthesis of diverse oligos DNA is primarily viewed as a carrier of information encoded in the sequence of bases, but the chemistry of the phosphodiester backbone is crucial to oligonucleotide stability and structure. Building on previous work in synthetic P(V) phosphorothioate coupling chemistry, Huang et al . developed two new reagents for making phosphorodithioate- and phosphate-based linkages (see the Perspective by Virta). The authors incorporated all of these reagents into a unified P(V)-based synthesis platform capable of running at high efficiency on a commercial automated solid-phase synthesizer. They demonstrate the flexibility of this system by producing oligonucleotides with all three linkage types in specific positions. Access to such precisely constructed molecules opens new approaches to therapeutic oligonucleotide design. —MAF

An operationally simple, scalable, and chemoselective method for the direct phosphorylation of alcohols using a P(V)-approach based on the Ψ-reagent platform is disclosed. The method features a broad substrate scope of utility in both simple and complex settings and provides access to valuable phosphorylated alcohols that would be otherwise difficult to obtain.

A pulsed discharge is introduced between two sequential pulse-modulated radio frequency glow discharges in atmospheric helium. The dependence of radio frequency discharge ignition on pulsed discharge intensity is investigated experimentally with the pulse voltage amplitudes of 650, 850, and 1250 V. The discharge characteristics and dynamics are studied in terms of voltage and current waveforms, and spatial-temporal evolution of optical emission. With the elevated pulsed discharge intensity of two orders of magnitude, the ignition of radio frequency discharge is enhanced by reducing the ignition time and achieving the stable operation with a double-hump spatial profile. The ignition time of radio frequency discharge is estimated to be 2.0 μs, 1.5 μs, and 1.0 μs with the pulse voltage amplitudes of 650, 850, and 1250 V, respectively, which is also demonstrated by the spatial-temporal evolution of optical emission at 706 and 777 nm.

<div><div><div><p>The early promise of gene-based therapies is currently being realized at an accelerated pace with over 155 active clinical trials for antisense compounds and multiple FDA-approved oligonucleotide therapeutics. Fundamental advances in this area are vital and present an unprecedented opportunity to both address disease states that have been resistant to other common modalities and improve the significant sustainability challenges associated with production of these complex molecules on a commercial scale. The advent of phosphoramidite coupling chemistry and solid-phase synthesis 40 years ago democratized oligonucleotide synthesis to the scientific community, paving the way for many of these stunning developments. The reliability and generality of this approach for the preparation of native phosphate-diesters is attributed to the high reactivity of phosphorus when in the P(III)-oxidation state versus the desired P(V), as it enables rapid P-heteroatom bond formation. However, the growing demand for more diverse phosphorus-based linkages has challenged the limits of this technology. For example, the phosphorothioate (PS) linkage, which stabilizes oligonucleotides towards nuclease cleavage, is universally employed in current oligonucleotide therapeutics but is generally incorporated in racemic form. Stereodefined PS oligonucleotides may have desirable biological and physical properties but are accessed with difficulty using phosphoramidite chemistry. Here we report a flexible and efficient [P(V)]-based platform that can install a wide variety of phosphate linkages at will into oligonucleotides. This approach uses readily accessible reagents and can efficiently install not only stereodefined or racemic thiophosphates, but can install any combination of (S, R or rac)-PS with native phosphodiester (PO2) and phosphorodithioate (PS2) linkages into DNA and other modified nucleotides. Importantly this platform easily accesses this diversity under a standardized coupling protocol with sustainably prepared, stable, P(V) reagents.</p></div></div></div>

<div><div><div><p>The early promise of gene-based therapies is currently being realized at an accelerated pace with over 155 active clinical trials for antisense compounds and multiple FDA-approved oligonucleotide therapeutics. Fundamental advances in this area are vital and present an unprecedented opportunity to both address disease states that have been resistant to other common modalities and improve the significant sustainability challenges associated with production of these complex molecules on a commercial scale. The advent of phosphoramidite coupling chemistry and solid-phase synthesis 40 years ago democratized oligonucleotide synthesis to the scientific community, paving the way for many of these stunning developments. The reliability and generality of this approach for the preparation of native phosphate-diesters is attributed to the high reactivity of phosphorus when in the P(III)-oxidation state versus the desired P(V), as it enables rapid P-heteroatom bond formation. However, the growing demand for more diverse phosphorus-based linkages has challenged the limits of this technology. For example, the phosphorothioate (PS) linkage, which stabilizes oligonucleotides towards nuclease cleavage, is universally employed in current oligonucleotide therapeutics but is generally incorporated in racemic form. Stereodefined PS oligonucleotides may have desirable biological and physical properties but are accessed with difficulty using phosphoramidite chemistry. Here we report a flexible and efficient [P(V)]-based platform that can install a wide variety of phosphate linkages at will into oligonucleotides. This approach uses readily accessible reagents and can efficiently install not only stereodefined or racemic thiophosphates, but can install any combination of (S, R or rac)-PS with native phosphodiester (PO2) and phosphorodithioate (PS2) linkages into DNA and other modified nucleotides. Importantly this platform easily accesses this diversity under a standardized coupling protocol with sustainably prepared, stable, P(V) reagents.</p></div></div></div>