Novel acyclonucleotides: synthesis and antiviral activity of alkenylphosphonic acid derivatives of purines and a pyrimidine

Design and Synthesis of New α-hydroxy β-fluoro/β-trifluoromethyl and Unsaturated Phosphonates from Carbohydrate-Derived Building Blocks via Pudovik and Horner–Wadsworth–Emmons Reactions

Herein, we present the application of fluorinated carbohydrate-derived building blocks for α-hydroxy β-fluoro/β-trifluoromethyl and unsaturated phosphonates synthesis. Pudovik and Horner–Wadsworth–Emmons reactions were applied to achieve this goal. The proposed pathway of the key reactions is supported by the experimental results, as well as quantum chemical calculations. The structure of the products was established by spectroscopic (1D, 2D NMR) and spectrometric (MS) techniques. Based on our data received, we claim that the progress of the Pudovik and HWE reactions is significantly influenced by the acidic protons present in the molecules as assessed by pKa values of the reagent.

Phosphorylation of arenes, heteroarenes, alkenes, carbonyls and imines by dehydrogenative cross-coupling of P(O)-H and P(R)-H

Organophosphorous compounds have recently emerged as a powerful class of compounds with widespread applications, such as in bioactive natural products, pharmaceuticals, agrochemicals and organic materials, and as ligands in catalysis. The preparation of these compounds requires synthetic techniques with novel catalytic systems varying from transition metal, photo- and electrochemical catalysis to transformations without metal catalysts. Over the past few decades, the addition of P-H bonds to alkenes, alkynes, arenes, heteroarenes and other unsaturated substrates in hydrophosphination and other related reactions via the above-mentioned catalytic processes has emerged as an atom economical approach to obtain organophosphorus compounds. In most of the catalytic cycles, the P-H bond is cleaved to yield a phosphorus-based radical, which adds onto the unsaturated substrate followed by reduction of the corresponding radical yielding the product.

β-Hydroxy- and β-Aminophosphonate Acyclonucleosides as Potent Inhibitors of Plasmodium falciparum Growth

Malaria is an infectious disease caused by a parasite of the genus Plasmodium, and the emergence of parasites resistant to all current antimalarial drugs highlights the urgency of having new classes of molecules. We developed an effective method for the synthesis of a series of β-modified acyclonucleoside phosphonate (ANP) derivatives, using commercially available and inexpensive materials (i.e., aspartic acid and purine heterocycles). Their biological evaluation in cell culture experiments and SAR revealed that the compounds' effectiveness depends on the presence of a hydroxyl group, the chain length (four carbons), and the nature of the nucleobase (guanine). The most active derivative inhibits the growth of Plasmodium falciparum in vitro in the nanomolar range (IC₅₀ = 74 nM) with high selectivity index (SI > 1350). This compound also showed remarkable in vivo activity in P. berghei-infected mice (ED₅₀ ∼ 0.5 mg/kg) when administered by the ip route and is, although less efficient, still active via the oral route. It is the first ANP derivative with such potent antimalarial activity and therefore has considerable potential for development as a new antimalarial drug.

Exogenous-oxidant-free electrochemical oxidative C-H phosphonylation with hydrogen evolution

We herein report a versatile and environmentally friendly electrochemical oxidative C-H phosphonylation protocol. This protocol features a broad substrate scope; not only C(sp2)-H phosphonylation, but also C(sp3)-H phosphonylation is tolerated well under exogenous-oxidant-free and metal catalyst-free electrochemical oxidation conditions.

The Stereospecific Preparation of (Z)-α-Stannyl-1-Alkenylphosphonates as Precursors of Stereodefined α-Substituted Vinylphosphonates

The radical hydrostannation of 1-alkynylphosphonates gives the ( Z)-α-stannyl-1-alkenylphosphonates 2 stereoselectively; 2 can be transformed into α-iodo-1-alkenylphosphonates and α-substituted vinylphosphonates with retention of configuration.

Silver-catalyzed synthesis of 2-arylvinylphosphonates by cross-coupling of β-nitrostyrenes with H-phosphites

An efficient protocol for stereoselective synthesis of vinylphosphonates has been developed via AgNO₃-catalyzed cross-coupling of β-nitrostyrenes with dialkyl H-phosphites under mild conditions.

Stereoselective synthesis of vinylphosphonates and phosphine oxides via silver-catalyzed phosphorylation of styrenes

An efficient and stereoselective synthesis of vinylphosphonates and phosphine oxides was developed starting from styrenes using AgNO₃ as the catalyst and K₂S₂O₈ as the oxidant. Various vinyl-phosphonates and phosphine oxides were synthesized in good yields with excellent regioselectivity.

Catalyst-free synthesis of cycloalkenyl phosphonates

The reactions described provide a facile and efficient access to cycloalkenyl phosphonates with good to excellent yields via Diels–Alder cycloadditions between alkynyl phosphonates and 1,3-dienes under catalyst-free conditions.

Palladium-catalyzed desulfitative C–P coupling of arylsulfinate metal salts and H-phosphonates

An efficient desulfitative C–P coupling was accomplished with versatile arylsulfinate metal salts and H-phosphonates.

Synthesis and study of (R)- and (S)-β-hydroxyphosphonate acyclonucleosides as structural analogues of (S)-HPMPC (cidofovir)

Modification of the acyclic chain highly impacts antiviral activity and recognition by human nmpks.

Ruthenium-catalyzed homo Diels-Alder [2 + 2 + 2] cycloadditions of alkynyl phosphonates with bicyclo[2.2.1]hepta-2,5-diene

Ruthenium-catalyzed homo Diels-Alder [2 + 2 + 2] cycloadditions between alkynyl phosphonates and bicyclo[2.2.1]hepta-2,5-diene were studied. The observed reactivity was found to be dependent on the presence of the phosphonate moiety. The Ru-catalyzed cycloaddition was compatible with a variety of aromatic and aliphatic substituted alkynyl phosphonates, providing the corresponding phosphonate substituted deltacyclenes in low to good yields (up to 88%).

Third-generation immucillins: syntheses and bioactivities of acyclic immucillin inhibitors of human purine nucleoside phosphorylase

ImmH (1) and DADMe-ImmH (2) are potent inhibitors of human purine nucleoside phoshorylase (PNP), developed by us and currently in clinical trials for the treatment of a variety of T-cell related diseases. Compounds 1 and 2 were used as templates for the design and synthesis of a series of acyclic immucillin analogues (8-38) in order to identify simplified alternatives to 1 and 2. SerMe-ImmG (8) and DATMe-ImmG (9) displayed the lowest inhibition constants of 2.1 and 3.4 pM, respectively, vs PNP. It was postulated that the flexible natures of 8 and 9 enabled them to adopt conformations resembling those of 1 and 2 within the active site of PNP and that the positioning of two hydroxyl groups was critical for picomolar activity. SerMe-ImmH (10, K(d) = 5.2 pM) was shown to be orally available in mice with a long biological residence time on blood PNP.

Novel three-component route to diastereoselective synthesis of trisubstituted vinylphosphonates using phosphites, acetylenic esters, and aroyl chlorides

Trisubstituted vinylphosphonates have been prepared via three-component reaction using phosphites, acetylenic esters, and aroyl chlorides in good yields. A variety of phosphites, activated acetylenes, and aroyl chlorides have been successfully employed in these reactions. In addition, three-component synthesis of vinylphosphonate provides exclusive E-olefin stereochemistry.

Microwave-assisted palladium-catalyzed cross-coupling of aryl and vinyl halides with H-phosphonate diesters

A general and efficient method for the microwave-assisted formation of the C-P bond was developed. Using a prevalent palladium catalyst, Pd(PPh3)4, a quantitative cross-coupling of various H-phosphonate diesters with aryl and vinyl halides was achieved in less than 10 min. The reactions occurred with retention of configuration at the phosphorus center and in the vinyl moiety. Using this protocol, several C-phosphonates, including those bearing nucleoside and cholesteryl moieties, were prepared in high yields.