Recent advances in the synthesis of 4'-truncated nucleoside phosphonic acid analogues.

The synthesis of five series of 4'-truncated nucleoside phosphonic acid analogues is discussed in this review: (1) 4'-truncated furanose nucleoside phosphonic acid analogues; (2) 4'-truncated pyrrolidine nucleoside phosphonic acid analogues; (3) 4'-truncated carbocyclic nucleoside phosphonic acid analogues; (4) 4'-truncated isoxazole nucleoside phosphonic acid analogues; (5) 4'-truncated miscellaneous nucleoside phosphonic acid analogues. Five different ways are used to make the phosphonate moiety: (i) Michaelis-Arbuzov reaction of RX (X = Br, I, OTf) with trialkyl phosphate; (ii) Lewis acid catalyzed Michaelis-Arbuzov reaction of glycoside with trialkyl phosphite; (iii) nucleophilic addition of a dialkyl phosphite to a carbonyl group; (iv) direct coupling reaction with amino alkyl phosphonate; (v) de novo synthesis of phosphonated-isoxazole and 1,3-dioxolane heterocycles from phosphonated starting materials. Their biological activity results are briefly discussed.

Recent Advances in the Synthesis of 5'-deoxynucleoside Phosphonate Analogs.

The present review focuses on the synthesis of cyclic 5'-deoxynucleoside phosphonate analogs. The formation of various phosphonate alkyl moieties is accomplished through (i) Wittig (or HWE) type condensation to the nucleoside aldehyde moiety; (ii) nucleophilic displacement reaction using phosphonate anion or Lewis acid; (iii) Arbuzov reaction; (iv) olefin cross-metathesis between vinyl phosphonates and vinylated nucleosides; and (v) radical reaction and Pd catalyzed alkyne. For the coupling of nucleobases with cyclic moieties, the Mitsunobu reaction and Sonogashira-type cross-coupling are usually applied.

Chemical Synthesis of Acyclic Nucleoside Phosphonate Analogs Linked with Cyclic Systems between the Phosphonate and the Base Moieties.

The syntheses of acyclic nucleoside phosphonate (ANP) analogs linked with cyclic systems are described in the present review. The purpose of the review is to report the methodology of ANP analogs and to give an idea on the synthesis of a therapeutic structural feature of such analogs. The cyclopropane systems were mainly prepared by diazomethane cyclopropanation catalyzed by Pd(OAc)2, intramolecular alkylation, Kulinkovich cyclopropanation, and use of difluorocyclopropane, and so forth.

Recent advances in the synthesis of cyclic 5'-nornucleoside phosphonate analogues.

Nucleoside phosphonates are isosteric, isopolar, and isoelectronic with phosphates. Nucleoside phosphonates can undergo enzymatic phosphorylation for conversion into the corresponding diphosphoryl phosphonates, which are naturally occurring nucleoside triphosphate analogues. The biological activity, which is mostly antiviral and antitumor but sometimes is as specific enzyme inhibitor, is briefly presented to help discover compounds with increased activity over natural nucleosides to provide structure-activity data.

Synthesis and antiviral evaluation of novel 2',2'-difluoro 5'-norcarbocyclic phosphonic acid nucleosides as antiviral agents.

A very efficient synthetic route to novel 2',2'-difluoro 5'-norcarbocyclic phosphonic acid nucleosides from but-3-en-1-ol 5 is described. The discovery of 2'-fluorinated furanose nucleoside 1 as a potent anti-HIV-1 agent has led to the synthesis and biological evaluation of 2'-modified 5'-norversions of the carbocyclic phosphonate nucleosides. The synthesized nucleoside analogues 18, 19, 23a, 23b, and 24 were tested for anti-HIV activity as well as cytotoxicity.

Synthesis and evaluation of novel 6',6'-difluoro 5'-deoxycarbocyclic phosphonic acid nucleosides as antiviral agents.

The authors describe highly efficient synthetic routes for the preparation of novel 6',6'-difluoro 5'-deoxycarbocyclic phosphonic acid nucleosides from 1,4-dihydroxy-2-butene. The discovery that the 6'-fluorinated carbocyclic nucleoside (2, EC₅₀ = 0.16 μM) is a potent anti-HSV-1 agent led to the syntheses and biological evaluations of 6'-modified 5'-deoxyversions of carbocyclic phosphonate nucleosides.

Synthesis of novel 3'-hydroxymethyl 5'-deoxythreosyl phosphonic acid nucleoside analogues as potent antiviral agents.

A very efficient synthetic route to novel 3'-hydroxymethyl 5'-deoxythreosyl phosphonic acid nucleosides was described. The discovery of threosyl phosphonate nucleoside (PMDTA, EC(50) = 2.53 μM) as a potent antihuman immunodeficiency virus (anti-HIV) agent has led to the synthesis and biological evaluation of 3'-modified 5'-deoxy versions of the threosyl phosphonate nucleosides.

Synthesis of novel 2'-spirocyclopropyl-5'- deoxyphosphonic acid furanosyl nucleoside analogues as potent antiviral agents.

Novel 5'-deoxyfuranosyl purine phosphonic acid analogues with 2 '-electropositive moiety, such as spirocyclopropanoid, were designed and synthesized from commercially available diethyl malonate. Condensation reaction successfully proceeded from a glycosyl donor 15 at low reaction temperature in Vorbruggen conditions to give desired phosphonate analogues 16b and 23b. The synthesized nucleotide analogues 19, 22, 26, and 29 were subjected to antiviral screening against HIV-1.

Design and synthesis of carbocyclic versions of furanoid nucleoside phosphonic Acid analogues as potential anti-hiv agents.

Novel 5'-norcarbocyclic adenine and guanine phosphonic acid analogues with 6',6'-difluorine moiety were designed and synthesized from commercially available epichlorohydrin 5. A regioselective Mitsunobu reaction successfully proceeded from an allylic functional group 16b at low reaction temperature in polar cosolvent to give purine phosphonate analogues 17 and 24, respectively. The purine nucleoside phosphonate and phosphonic acid analogues were subjected to antiviral screening against HIV-1.

Synthesis of novel 4'-cyclopropyl-5'-norcarbocyclic adenosine phosphonic acid analogues.

Novel 4'-cyclopropyl-5'-norcarbocyclic adenosine phosphonic acid analogues were designed and racemically synthesized from propionaldehyde 5 through a de novo acyclic stereoselective route using triple Grignard addition and ring-closing metathesis (RCM) as key reactions. To improve cellular permeability and enhance the anti-HIV activity of this phosphonic acid, SATE phosphonodiester nucleoside prodrug 23 was prepared. The synthesized adenosine phosphonic acids analogues 17, 18, 19, 21, and 23 were subjected to antiviral screening against HIV-1.