2- and 3-Fluoro-3-deazaneplanocins, 2-fluoro-3-deazaaristeromycins, and 3-methyl-3-deazaneplanocin: Synthesis and antiviral properties

2- and 3-Fluoro-3-deaza-1',6'-isoneplanocin: Synthesis and antiviral properties (including Ebola and Marburg)

To extend the antiviral properties of 2- and 3-fluoro-3-deazaneplanocins into the evolving 3-deaza-1',6'-isoneplanocin library, 2- (11) and 3-fluoro-1',6'-iso-3-deazaneplanocin A (12) have been explored. The requisite synthesis began with an Ullmann reaction by coupling of a protected cyclopentenyl iodide with either 2-fluoro- or 3-fluoro-3-deazaadenine. Target 12 displayed significant activity towards 5 viruses (μM): H1N1 (EC₅₀ < 0.36, CC₅₀ > 357, SI > 1000), hepatitis B virus (EC₅₀ 1.28, CC₅₀ > 357, SI > 279), norovirus (EC₅₀ 0.64, CC₅₀ > 357, SI > 558), Ebola (EC₅₀ < 0.1, CC₅₀ > 100, SI > 1000), and Marburg (EC₅₀ < 0.1, CC₅₀ > 100, SI > 1000). On the other hand, while 11 showed limited antiviral effects, its toxicity was significant, precluding any further usefulness.

Enantiomeric 4'-truncated 6'-fluoro-3-deazaneplanocin and its 3-bromo derivative: Synthesis and antiviral properties, including Ebola and Marburg

In seeking to increase the library of fluorine containing adenine-derived carbocyclic nucleoside antiviral candidates, d-like and l-like 6'-fluoro-3-deazaneplanocin and its 3-bromo derivative lacking the 4'-hydroxylmethylene substituent (2/3 and 4/5, respectively) are presented. Their synthesis was accomplished from d-ribose by developing a more facile precursor route than suggested by the literature. The 2/4d-like pair displayed significant anti-filo virial properties while the enantiomeric l-like congeners 3/5 were inactive. Target compounds 2/4 also were active towards measles and norovirus. The effect of 2/4 is further evidence of the role fluoro-derived adenine carbocyclic nucleoside can play in antiviral drug discovery. Furthermore, the simplicity of their synthesis lends them to more efficacious analogs and to scale-up optimization. There were no other relevant antiviral properties for 2/3 and 4/5 (except BK polyomavirus for 3/5).

Synthesis of D-like and L-like 5'-fluoro-5'-deoxy-1',6'-isoneplanocins and their antiviral activity including Ebola

In exploring the 1',6'-isoneplanocin structural framework for antiviral compound development, both the D-like and L-like 5'-fluoro-5'-deoxy analogs have been synthesized from readily available cyclopentenyl iodides and adenine in five steps. Antiviral evaluation found D-like 5'-fluoro-5'-deoxy-1',6'-isoneplanocin to display less broad-spectrum antiviral effects than the parent D-like including weaker activity against Ebola and norovirus. The L-like enantiomer was devoid of any activity, contrary to the parent L-like compound.

l-like 3-deazaneplanocin analogues: Synthesis and antiviral properties

The potent antiviral properties of 3-deazaneplanocin, 3-deaza-isoneplanocins (1) and recently discovered l-like carbocyclic nucleosides (2, 3 and 4) prompted us to pursue rationally conceived l-like 3-deazaneplanocin analogues. The synthesis of those analogues including l-like 3-deazaneplanocin (5), l-like 3-bromo-3-deazaneplanocin (6), and l-like 5'-fluoro-5'-deoxy-3-deazaneplanocin (7), was accomplished from a common intermediate, (-)-cyclopentenone (8). Antiviral analysis found 5 and 6 to display favorable activity against the Ebola virus, as expected for 3-deazaadenine carbocyclic nucleosides. Compound 5 also showed activity against arenaviruses, including Pinchinde and Tacaribe.

Recent update on anti-dengue drug discovery

Dengue is the most important arthropod-borne viral disease of humans, with more than half of the global population living in at-risk areas. Despite the negative impact on public health, there are no antiviral therapies available, and the only licensed vaccine, Dengvaxia^®, has been contraindicated in children below nine years of age. In an effort to combat dengue, several small molecules have entered into human clinical trials. Here, we review anti-DENV molecules and their drug targets that have been published within the past five years (2014-2018). Further, we discuss their probable mechanisms of action and describe a role for classes of clinically approved drugs and also an unclassified class of anti-DENV agents. This review aims to enhance our understanding of novel agents and their cognate targets in furthering innovations in the use of small molecules for dengue drug therapies.

Tuning Cross-Coupling Approaches to C3 Modification of 3-Deazapurines

A general approach to C3 modification of purine scaffold through various types of cross-coupling reactions has been established. Tuning substrate electronics and reaction conditions resulted in the development of highly efficient sp²-sp, sp²-sp², and sp²-sp³ cross-coupling conditions for modification of 3-deazaadenine to access C3-modified adenine and hypoxanthine scaffolds. The optimized methodologies to access the corresponding 3-deazaadenosine phosphoramidites for solid-phase DNA synthesis have been demonstrated.