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Herein, we report the preparation of enantiomerically pure forms of 2,3-dihydrobenzofuran-3-ol (1), chroman-4-ol (2), thiochroman-4-ol (3), 1-(furan-2-yl) ethanol (5) and 1-(thiophen-2-yl) ethanol (6), through a kinetic resolution catalysed by Candida antarctica lipase B/Na2CO3 hydrolysis sequence in organic media. The (R)-furnished alcohols and the (S)-remained acetates are recovered enantiopures (ee >99%, E ≫ 200, Conv = 50%). Those ideal enzymatic kinetic resolution (EKRs) are well incorporated to the Mitsunobu inversion protocol in a one pot procedure to give (S)-heterocyclic acetates (1a–3a) in good to high enantiomeric excess (88%–92% ee). Whilst, the (S)-heteroaromatic acetates (5a and 6a) are given with moderate enantiomeric excess (51%–62% ee). All the (S)-acetates are given in good isolated chemical yields (>80%) allowing to overcome the maximum of 50% yield which could be usually reached in a regular kinetic resolution processes. [ABSTRACT FROM AUTHOR]

The total synthesis of 14 membered macrolide Pestalotioprolide C and C7-epi- Pestalotioprolide C were accomplished starting from commercially available D-Mannitol by Stereoselective synthetic approach. The key reactions involved are Mitsunobu reaction, Regioselective ring opening of chiral epoxide and ring-closing metathesis reactions (RCM). [ABSTRACT FROM AUTHOR]

Alkylation of thiopurine derivatives with alcohols by the Mitsunobu reaction are reported in moderated to good yields. The method was applied in synthesis of number of thiopurine and thiopurine ribosides derivatives. [ABSTRACT FROM AUTHOR]

Immunomodulators are assigned as a robust tool for the treatment of various medical conditions like AIDS, cancer and autoimmune diseases. In this work, we have synthesized a series of fluoxetine-based small-molecule immunomodulators. Molecules were synthesized by a convergent strategy, where mitsunobu reaction was conducted to synthesize the common starting material. The novel analogues displayed immunomodulatory potential as indicated by the anti-inflammatory effect derived through the compound's T cell proliferation inhibitory property. The synthesized novel analogues manifested encouraging biological responses, assure their application as immunomodulators. [ABSTRACT FROM AUTHOR]

S-(−)-trans-Verbenol (1) and its antipode, R-(+)-trans-verbenol (1′) have been confirmed as the critical pheromone components of bark beetles. Synthesis of these two active secondary alcohols (1 and 1′) from commercially available starting materials S-α-pinene and R-α-pinene was reported. The key steps were mainly depended on the effective SN2 stereo-inversion of the hydroxy group of sterically hindered alcohols (3 and 3′), using Mitsunobu reaction or hydrolysis of mesylate ester, alternatively. Our results provide a new and stereo-selectivity way to obtain optically active insect pheromones. [ABSTRACT FROM AUTHOR]

To find a potent α-glucosidase inhibitor, 24 tyrosol derivatives with different substituents located at the meta, ortho, or para position of the phenyl group have been synthesised via the Mitsunobu reaction, characterised by 1H NMR, 13C NMR, ESI-MS and IR and evaluated for inhibition. The derivatives possessed varying degrees of in vitro inhibitory activity against α-glucosidase and a relationship between the structure and activity was subsequently established for all compounds. Two of these compounds with substituents at the para position showed significant inhibitory effects surpassing that of the control standard acarbose. Molecular docking studies performed to better understand the binding interactions between the enzyme and the two most active compounds showed substantial binding within the active site of α-glucosidase. Taken together, these results indicate that the position of the substituent plays a crucial role in this inhibition and may facilitate the development of new α-glucosidase inhibitors. [ABSTRACT FROM AUTHOR]

The need of long-term treatment for chronic HBV, emergence of drug-resistant viruses and inefficiency of currently approved therapies to eliminate covalently closed circular DNA (cccDNA), mandates identification of potent and selective inhibitors of HBV replication with novel mechanisms of action. Entecavir, a carbocyclic guanosine nucleoside analog, is the most potent inhibitor of HBV replication on the market. Moreover, the naturally occurring carbocyclic nucleosides aristeromycin are known for their wide range of antiviral activities. In this research, we have utilized BINAP directed rhodium catalyzed reductive carbocyclization of 1,6-enynes (8a–b) through asymmetric hydrogenation which is an approach, not yet explored in carbocyclic sugar synthesis. Interestingly, we obtained exclusive anti-(9a) and Z-anti(9b) carbocyclic sugars. The new aristeromycin analogs (10a–b) with scaffold combination of entecavir and aristeromycin were then synthesized using the Mitsunobu reaction followed by deprotection. [ABSTRACT FROM AUTHOR]

An efficient stereoselective synthesis 3α- and 3β-aminoandrostan-17-one and 3α-amino dehydroepiandrosten-17-one based on a Mitsunobu reaction has been developed, using azide as the ammonia equivalent. All the products were isolated in high yield. [ABSTRACT FROM AUTHOR]

Syntheses of α-branched alkyl and aryl substituted 9-[2-(phosphonomethoxy)ethyl]purines from substituted 1,3-dioxolanes have been developed. Key synthetic precursors, α-substituted dialkyl [(2-hydroxyethoxy)methyl]phosphonates were prepared via Lewis acid mediated cleavage of 1,3-dioxolanes followed by reaction with dialkyl or trialkyl phosphites. The best preparative yields were achieved under conditions utilizing tin tetrachloride as Lewis acid and triisopropyl phosphite. Attachment of purine bases to dialkyl [(2-hydroxyethoxy)methyl]phosphonates was performed by Mitsunobu reaction. Final α-branched 9-[2-(phosphonomethoxy)ethyl]purines were tested for antiviral, cytostatic and antiparasitic activity, the latter one determined as inhibitory activity towards Plasmodium falciparum enzyme hypoxanthine-guanine-xanthine phosphoribosyltransfesase. In most cases biological activity was only marginal. [ABSTRACT FROM AUTHOR]

Five chiral compounds were designed and synthesized using the Mitsunobu reaction to act as chiral inducers (i.e., chiral dopants) for the transformation of a nematic liquid crystal (LC) (4-n-octoxy-4′-cyanobiphenyl) into a cholesteric LC. These chiral inducers contain two types of chiral alkyl chains with different kinds of achiral mesogenic cores (biphenylcarboxylate, biphenoxy, and cyanobiphenoxy). We observed that the achiral mesogenic cores affected the helical twisting power in terms of both induction strength and helicity (left-/right-hand introduction). All the ester type inducers exhibited a positive Cotton effect and right-hand helical twisting power (HTP). However, ethers exhibited a negative Cotton effect and left-hand HTP. The microscopic HTPs (βM) of these inducers demonstrate a linear relation with their optical activities (ellipticity near the absorption maximum). Further, the time-dependent density functional theory (TD–DFT) calculation using the B3LYP/6-311++G (d, p) method has been used to predict the circular dichroism spectra of these inducers. The predicted optical activity was observed to be in accordance with that observed in the experimental result. This study proposes a method for predicting the HTP of chiral inducers that can be applied to achieve polymerization in the reaction fields of cholesteric LCs. [ABSTRACT FROM AUTHOR]

Reported is an efficient synthesis of adenyl and uridyl 5′-tetrachlorophthalimido-5′-deoxyribonucleosides, and guanylyl 5′-azido-5′-deoxyribonucleosides, which are useful in solid-phase synthesis of phosphoramidate and ribonucleic guanidine oligonucleotides. Replacement of 5′-hydroxyl with tetrachlorophthalimido group was performed via Mitsunobu reaction for adenosine and uridine. An alternative method was applied for guanosine which replaced the 5′-hydroxyl with an azido group. The resulting compounds were converted to 5′-amino-5′-deoxyribonucleosides for oligonucleotide synthesis. Synthetic intermediates were tested as antimicrobials against six bacterial strains. All analogs containing the 2′,3′-O-isopropylidine protecting group demonstrated antibacterial activity against Neisseria meningitidis, and among those analogs with 5′-tetrachlorophthalimido and 5′-azido demonstrated increased antibacterial effect. [ABSTRACT FROM PUBLISHER]

Mitsunobu reaction of partially acylated uridine proceeds with high regioselectivity for intramolecular SN2 anhydro linkage closuring. Under the reaction conditions, an isomeric mixture of diacyl uridine derivatives with either free 2′- or 3′-hydroxyl group was transformed into a single cyclonucleosidic product, 2,2′-anhydro-3′,5′-di-O-acyluridine. This paper presents a possible mechanism of the reactions, the explanation of observed phenomenon based on semiempirical and density functional theory (DFT) calculations and possible utility of this synthetic pathway. [ABSTRACT FROM AUTHOR]

Carbocyclic nucleosides are considered as nucleoside mimetic having high therapeutic potentials, however diverse exploration is still limited due to their synthetic difficulties. The major challenges are associated with the preparation of new base and carbocyclic sugar key intermediates. The modified base may provide conformational advantage to achieve better nucleoside mimetics and may also help in increasing the drug-like properties. In this manuscript, we report the use of acetamidine hydrochloride to synthesize 6-methyl-4-amino-pyrazolo[3,4-d]pyrimidine base and regioselective synthesis of six new carbocyclic nucleosides (6a-f) for antiviral evaluation. Theoretical investigations were carried out on the basis of thermodynamic and kinetic stability using MM based energy optimizations and QM based transition state search for the significant regioselectivity, which was further experimentally analyzed by NOE and UV spectroscopy. [ABSTRACT FROM AUTHOR]

A dehydrative annulation strategy involving an intramolecular ring closure under a Mitsunobu-type reaction condition has been used for the construction of octahydroindolizine framework successfully. This strategy that was reported to be unsuccessful when applied to a similar system allowed us to perform a diastereoselective synthesis of (6R,8aS)-octahydroindolizin-6-ol [a precursor of (–)-8a-epidesacetoxyslaframine] starting from commercially available chiral (S)-epichlorohydrin via a piperidine intermediate, i.e., (3R,6S)-6-(3-hydroxypropyl)piperidin-3-ol. The methodology has potential to afford a library of optically pure small molecules of pharmacological importance based on the related indolizine framework. [ABSTRACT FROM AUTHOR]

A series of new alkyl, tosyl, acetyl, andtert-butoxycarbonyl derivatives of 2-(2-aminoethyl)-phthalazinones were efficiently synthesized by reaction of lactams withN-Boc-,N-acetyl-, orN,O-ditosyl derivatives ofN-methylethanolamine in the presence of MeONa or under Mitsunobu reaction conditions. Selected compounds were converted into corresponding 2-[2-(methylamino)ethyl]phthalazinones in good yields. [ABSTRACT FROM PUBLISHER]

An efficient approach toward the construction of multistereogenic binaphthol (BINOL)–derived alkaloids with C2-axial and sp3central chirality has been accomplished. The reaction of BINOL and cinchona alkaloids was occurred smoothly under the Mitsunobu conditions, which led to the synthesis of a new family of complicated functional molecules based on chiral BINOL and cinchona alkaloids. In addition, on the basis of the experimental results, we provided a possible explanation for the intramolecular tertiary amine-induced retention of configuration at C9 of cinchona alkaloids while the inversion of configuration was observed with general alcohols under classic Mitsunobu conditions. [ABSTRACT FROM AUTHOR]

Novel 5′-deoxycarbocyclic purine phosphonic acid analogs with the 4′-electropositive moiety, fluorine were designed, and synthesized from glyceraldehyde. The cyclopentenol intermediate,9, was successfully synthesized by the ring-closing metathesis of divinyl8. The condensation reaction of cyclopentanol15with purine bases under Mitsunobu conditions successfully afforded the desired phosphonate analogs. The synthesized nucleoside phosphonic acid analogs,19,22,26, and29, were subjected to antiviral screening against human immunodeficiency virus (HIV)-1. Guanine phosphonic acid analog29showed significant anti-HIV activity (EC50= 10.3 μM). [ABSTRACT FROM AUTHOR]

The use of the Mitsunobu reaction for the synthesis ofN,N-diethylbenzamides affordsortho-,meta-, andpara-substituted benzamides containing both electron-donating and electron-withdrawing groups. While the preparation of numerous functional groups has been efficiently demonstrated employing the Mitsunobu reaction, our methodology represents the first application of the Mitsunobu reaction for the construction of benzamides using benzoic acid and amine starting materials. Moreover, this synthetic transformation is believed to proceed via a nonclassical mechanism involving the existence of an acyloxyphosphonium ion. [Supplementary materials are available for this article. Go to the publisher's online edition ofSynthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.] [ABSTRACT FROM AUTHOR]

A convenient and efficient synthesis of 1,6-anhydro-2,4-dideoxy-β-D-threo-hexopyranose (2,4-dideoxy-levoglucosan) from levoglucosan has been developed. The method uses cheap reagents and requires only crystallization and distillation for preparation of pure product on a multigram scale. [Supplementary materials are available for this article. Go to the publisher's online edition ofSynthetic Communications®for the following free supplemental resource: Full experimental and spectral details.] [ABSTRACT FROM PUBLISHER]

Mitsunobu coupling of 3-hydroxymethylbenzofurans witho-iodophenols affords 3-(2-iodophenoxy)methylbenzofurans which under go a useful 6-endo Heck cyclization under Jeffery conditions to afford pterocarpene-type heterocycles. The unsubstituted parent pterocarpene thus prepared was readily converted to coumestan via subsequent PCC oxidation. Supplemental materials are available for this article. Go to the publisher's online edition ofSynthetic Communications®to view the free supplemental file. [ABSTRACT FROM PUBLISHER]

A series of thiacalix[4]monocrowns in1,3-alternateconformation containing thioalkyl fragments was synthesized by the reaction of corresponding distal thiacalix[4]arene derivatives with oligoethylene glycols using a Mitsunobu protocol. [ABSTRACT FROM AUTHOR]

4-(2-Perfluorohexyl)-ethoxy-4′-cyanobiphenyl (F6H2OCB) and 4-(2-perfluorooctyl)-ethoxy-4′-cyanobiphenyl (F8H2OCB) were synthesised by Mitsunobu reaction. Liquid crystalline state of F6H2OCB and F8H2OCB was studied by differential scanning calorimetry (DSC) and microscopic observation. Broken fan-shaped texture, which is the characteristic of smectic C phase, was observed between 89.4°C and 162.0°C for F6H2OCB and between 103.7°C and 182.1°C for F8H2OCB. Such a stable smectic C liquid crystal (LC) is rarely reported. Smectic C LC can be transformed to ferroelectric smectic C* by the addition of a chiral compound. Smectic K phase was observed at room temperature for both F6H2OCB and F8H2OCB, and perfluoroalkyl chains were located up and down alternatively. Smectic K phase was proved by the comparison ofd(interlayer distance) andL(calculated dimer molecular length) and the non-monotonic and slow decay of the intensities of 00ℓ reflections in X-ray diffraction (XRD). [ABSTRACT FROM AUTHOR]

A facile, simple, and high-yielding protocol for synthesis of novel glycosyl azetidines was developed from glycosyl β-amino alcohols via intramolecular cyclization under Mitsunobu reaction conditions. [ABSTRACT FROM AUTHOR]

Both enantiomers of a series of δ-lactones (e.g., δ-decalactone, δ-dodelactone, and δ-hexadecalactone) were synthesized stereoselectively by Novozym 435–catalyzed resolution. Furthermore, only (S)-enantiomers of δ-lactones were synthesized with a combination of Novozym 435–catalyzed resolution and Mitsunobu reaction. [ABSTRACT FROM PUBLISHER]

Starting from commercially available piperazine-2-carboxylic acid, a series of novel 2-aryl and 2-benzyl substituted imidazopyrazinone were prepared. The intermediates 5a–g were obtained through facile Buchwald–Hartwig coupling reaction, and the effects of catalyst, base, and solvent on the coupling reaction were investigated. The optimal reaction conditions for the coupling reaction were PdCl2(dppf)/NaO-t-Bu/toluene. [ABSTRACT FROM PUBLISHER]

Pyroglutamates have been acknowledged as useful chiral synthons for the synthesis of many bioactive natural products, ACE inhibitors, and conformationally constrained peptides. Though the reactivity differences between two differential carbonyl groups have been well exploited, there is still a dearth of publications on the N-alkylation/acylation of native pyroglutamate as such, due to the relatively low reactivity of NH of pyroglutamates. In the present communication, we report for the first time a simple and efficient methodology for the N-alkylation/acylation of pyroglutamate via Mitsunobu reaction. [image omitted] [ABSTRACT FROM AUTHOR]

This is the first report on applying the Mitsunobu protocol for the synthesis of various α-acyloxyphosphonates using 4,4′-azopyridine and PPh3 with diverse aromatic and aliphatic carboxylic acids. Under these conditions, diethyl azodicarboxylate (DEAD) as the traditional reagent for Mitsunobu reaction is not efficient. The insoluble pyridine hydrazine byproduct can be simply isolated and recycled to its azopyridine by an oxidation reaction and reused again. [Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental resource: Characterization data of compounds 3a–3z2 and NMR spectra.] GRAPHICAL ABSTRACT [ABSTRACT FROM AUTHOR]

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. Adenine analogue 21 and its SATE prodrug 29 show significant anti-HIV activity in MT-4 cell lines. [ABSTRACT FROM AUTHOR]

Novel 5′-norcarbocyclic adenosine phosphonic acid analogues with 6′-electropositive moiety such as spirocyclopropane were designed and synthesized from the commercially available diethylmalonate 5. Regioselective Mitsunobu reaction proceeded in the presence of an allylic functional group at a low reaction temperature in polar cosolvent [dimethylformamide (DMF)/1,4-dioxane] to give purine analogue 15. To improve cellular permeability and enhance the anti-human immunodeficiency virus (HIV) activity of this phosphonic acid, a SATE phosphonodiester nucleoside prodrug 23 was prepared. The synthesized adenosine phosphonic acids analogues 18–21 and 23 were subjected to antiviral screening against HIV-1. [ABSTRACT FROM AUTHOR]

A set of 11-thiofunctionalized derivatives of natural (-)-lupinine have been synthesized using phosphine-based redox type methods such as Hata and Mitsunobu reactions. [ABSTRACT FROM AUTHOR]

Chiral γ-lactones of both enantiomers were synthesized with more than 90% optical purities. The key step was Novozym 435-catalyzed hydrolysis of racemic N-benzyl-4-acetoxyalkylamides. Additionally, because (R)-γ-lactones are predominant in apricot, mango, peach, passion fruit, and strawberry, synthesis was attempted using only one enantiomer selectively. The (R)-enantimer was synthesized with more than 80% total yield and more than 90% optical purity by a combination of Novozym 435-catalyzed hydrolysis and the Mitsunobu reaction. [ABSTRACT FROM AUTHOR]

Six kinds of (S)-γ-lactones [e.g., (S)-γ-decalactone, (S)-γ-undecalactone, and (S)-γ-jasmolactone] were synthesized with 71-88% yields and >97% optical purities by combining lipase-catalyzed resolution with the Mitsunobu reaction. [ABSTRACT FROM AUTHOR]

The exomethylene of 6 was successfully constructed from the aldehyde 5 using Eschenmoser's reagents. A triene compound 7 was cyclized successfully using Grubbs' II catalyst to give an exomethylene carbocycle nucleus for the target compound. A Mitsunobu reaction was successfully used to condense the natural bases (adenine, thymine, uracil, and cytosine). The synthesized cytosine analogue 20 showed moderate anti-HIV activity (EC50 = 10.67 μM). [ABSTRACT FROM AUTHOR]

Two N-Fmoc and S,S'-protected α-amino acids were synthesized by introducing the derivatives of dithioether into a Tyrosine side chain under the Mitsunobu protocol using the diisopropylazodicarboxylate/triphenylphosphine (DIAD/TPP) system. These amino acids provide a potential use in peptide chemistry. [ABSTRACT FROM AUTHOR]

A series of chiral cyclosulfamides and oxazolidinon-2-ones have been synthesized starting from aminoacids. Regioselective substitution of these pseudopyrimidic heterocyles was carried out under Mitsunobu conditions. Best substitution results were obtained by preliminary deprotection of cyclosulfamides and their condensation with β -D-ribofuranose. Chiral oxazolidin-2-ones were coupled directly with D-ribofuranose. All compounds were tested against HSV-2, VV and SV viruses. Two compounds 6b and 6e showed significant activities against HSV-type 1. [ABSTRACT FROM AUTHOR]

Synthesis of eight nucleoside analogues 4-11 with a methylenecyclobutane unit is described. Wittig reaction with 2-hydroxymethylcyclobutanone 12 gave a mixture of Z (13) and E (14) derivatives, which was separated before functional modifications. The heterocyclic moieties were introduced via a Mitsunobu reaction either on the saturated chain or on the unsaturated chain. When adenine was used in this reaction, only the N-9 substitution products were obtained. Removal of the protecting groups provided the target products. [ABSTRACT FROM AUTHOR]

The asymmetric synthesis of (+)‐ epi ‐cytoxazone, a stereoisomer of potent cytokine modulator cytoxazone, starting from anisaldehyde in six steps, is described. The required configuration was established via Sharpless kinetic resolution followed by the Mitsunobu reaction. [ABSTRACT FROM AUTHOR]

A phtalimido group can be readily introduced at the 5?-position of N -Boc ribostamycin 6 under Mitsunobu reaction conditions. However, in the case of N -Boc neomycin B 4 a competitive bicyclization process occurred within the ring IV of the antibiotic, which led to compound 8, whose structure was fully elucidated by NMR spectroscopic methods. Accordingly, particular care must be exercised to achieve this chemical modification of the four-ring antibiotic. [ABSTRACT FROM AUTHOR]

S ‐Glycosyl L‐aspartic acid building blocks were synthesized starting from 1‐thiosugars by reaction with 5‐aminopentanol and suitably protected L‐aspartic acid pentafluorophenyl ester in a one‐pot procedure under Mitsunobu conditions using 1,1′‐azodicarbonyl dipiperidine and trimethyl phosphine. The method allowed for the preparation of S ‐glycosyl amino acid building blocks in one step without protection of the amino function for the Mitsunobu condensation. Alternatively, the title compounds were prepared by a stepwise approach via 5‐aminopentyl 1‐thioglycosides. [ABSTRACT FROM AUTHOR]

Enantiomerically pure carbocyclic 2′-deoxy-3′-azidothymidine monophosphate (AZTMP) and carba -2′deoxy-3′-thiocyanatothymidine monophosphate were synthesized to study their behavior toward their phosphorylation by thymidylate kinase. The nucleotides were synthesized starting from the parent nucleosides by an alkaline hydrolysis of the corresponding cyclo Sal-phosphate triesters. [ABSTRACT FROM AUTHOR]

The Mitsunobu cyclization of p - t -butylthiacalix[4]arene with glycols was expanded to oligoethylene glycol analogues composed of O, S and N atoms in the chain. In this way a number of 1,3-thiacalix[4]monocrowns have been synthesized, offering simple and general access to a large variety of crowned thiacalixarenes. The binding properties of some ligands towards transition metal cations have been studied by 1 H NMR, UV/Vis spectroscopic and potentiometric methods. [ABSTRACT FROM AUTHOR]

Methyl 2-acetamido-4-amino-2,4,6-trideoxy-α-D-galactopyranoside (10) was synthesized from D-glucosamine hydrochloride in eight steps in an overall yield of 31%. Key steps include the selective benzoylation at 0-3 of methyl 2-acetamido- 2,6-dideoxy-α-D-glucopyranoside in 89% yield and the subsequent Mitsunobu reaction using diphenylphosphoryl azide as the azide source which proceeded in 92% yield. Di- and mono-benzyloxycarbonyl derivatives of 10 were also prepared. [ABSTRACT FROM AUTHOR]

A general synthetic approach to various isoxanthopterin-nucleosides starting from 6-methyl-2-methylthio-4(3H), 7(8H)-pterdinedione (1) has been developed. Ribosylation with 1-O-acetyl-2,3,5-tri-O-benzoyl-β-D-ribofuranose via the silyl-method led to 2 and reaction with 1-chloro-2-deoxy-3,5-di-O-p-toluoyl-α-D-ribofuranose using the DBU-method afforded 28. Protection of the amide function at O[sup4] by benzylation to 5 and by a Mitsunobu reaction with 2-(4-nitrophenyl)ethanol to 29 gave soluble intermediates which can be oxidized to the corresponding 2-methylsulfonyl derivatives 8 and 30, respectively. Nucleophilic displacement reactions of the highly reactive 2-methylsulfonyl functions by various amines proceeded under mild conditions to isoxanthopterin-N[sub8]-ribo- (11-17) and 2'-deoxyribomucleosides (31-33). Debenzylation can be achieve by Pd-catalyzed hydrogenation (9 to 19) and cleavage of the npeprotecting group (31, 32 to 34, 35) works well with DBU by β-elimination. [ABSTRACT FROM AUTHOR]

The Mitsunobu reaction was applied to prepare, in one step, purine N³,5'-cyclonucleosides 10a-d. A subsequent ring opening in the ribose moiety of the resultant N³,5'-nucleosides by sodium periodate led to the corresponding N³,5'-cyclo-2',3'-seconucleosides. These products consist of 5-, 6-, and 7-membered tricyclic system which is the basic skeleton of TIBO derivatives, known antiviral agents. [ABSTRACT FROM AUTHOR]

Novel compound 1, as the first example of cyclic ADP-ribose analogs containing a pyrimidine residue, was synthesized by a chemical strategy employing a Mitsunobu reaction for the condensation of the glucosyl moiety on protected uridine, and a Matsuda procedure for the cyclization step. [ABSTRACT FROM AUTHOR]

Reaction of N-Boc neomycin with triphenylphosphine and diissopropyl azodicarboxylate in either toluene or THF results in an epoxide in ring IV, not an aziridine or azetidine as previously reported. [ABSTRACT FROM AUTHOR]