D-ribose Derivative Research Articles

Total Synthesis of Penicyclone A Using a Double Grignard Reaction.

We describe the first total synthesis of penicyclone A, a novel deep-sea fungus-derived polyketide, and a reevaluation of its antimicrobial activity. The synthesis of this unique spirolactone was achieved in 10 steps starting from a known d-ribose derivative. The key steps include a double Grignard reaction for the diastereoselective construction of the chiral tertiary alcohol intermediate, tandem oxidation/cyclization, and photooxygenation, followed by an oxidative rearrangement to introduce the enone functionality.

Total Synthesis of Resiniferatoxin Enabled by Photocatalytic Decarboxylative Radical Cyclization.

Resiniferatoxin (1) is a complex daphnane diterpenoid with a highly oxygenated 5/7/6-membered ABC-ring system. Here we report a new synthetic route to 1 that requires 27 steps from a starting d-ribose derivative. The carbon spacer and A-ring are sequentially attached to the C-ring by radical allylation and Stille coupling reactions, respectively. An Ir(III)-catalyzed photoinduced decarboxylative radical reaction then forged the sterically hindered bond between the tetra- and trisubstituted carbons to cyclize the central seven-membered B-ring.

Inositol Adenophostin: Convergent Synthesis of a Potent Agonist of d-myo-Inositol 1,4,5-Trisphosphate Receptors.

d-myo-Inositol 1,4,5-trisphosphate receptors (IP3Rs) are Ca2+ channels activated by the intracellular messenger inositol 1,4,5-trisphosphate (IP3, 1). The glyconucleotide adenophostin A (AdA, 2) is a potent agonist of IP3Rs. A recent synthesis of d-chiro-inositol adenophostin (InsAdA, 5) employed suitably protected chiral building blocks and replaced the d-glucose core by d-chiro-inositol. An alternative approach to fully chiral material is now reported using intrinsic sugar chirality to avoid early isomer resolution, involving the coupling of a protected and activated racemic myo-inositol derivative to a d-ribose derivative. Diastereoisomer separation was achieved after trans-isopropylidene group removal and the absolute ribose–inositol conjugate stereochemistry assigned with reference to the earlier synthesis. Optimization of stannylene-mediated regiospecific benzylation was explored using the model 1,2-O-isopropylidene-3,6-di-O-benzyl-myo-inositol and conditions successfully transferred to one conjugate diastereoisomer with 3:1 selectivity. However, only roughly 1:1 regiospecificity was achieved on the required diastereoisomer. The conjugate regioisomers of benzyl derivatives 39 and 40 were successfully separated and 39 was transformed subsequently to InsAdA after amination, pan-phosphorylation, and deprotection. InsAdA from this synthetic route bound with greater affinity than AdA to IP3R1 and was more potent in releasing Ca2+ from intracellular stores through IP3Rs. It is the most potent full agonist of IP3R1 known and .equipotent with material from the fully chiral synthetic route.

Chiral coordination polymers based on a new d-ribose derivative ligand: Syntheses, structures and probe functions

Three coordination polymers (CPs) {[CuL2Br]Br·6H2O}∞ (1), {[CuL2Cl2]·2.5CH3OH·3.5H2O}∞ (2) and {[NiL2(NO3)2]·CH3CN·3CH3OH·H2O}∞ (3) were prepared using a new d-ribose derivative ligand L (L = 1,2,3,4-tetrakisisoniacyl-β-l-ribopyranose). X-ray single crystal analysis revealed that 1–3 all crystallized in the triclinic P1 space group, all the CPs have 1-D metallomacrocycle strand structures, all the L ligands in the CPs show the same chiral type, and there are four pyridyls bonding with each metal centre arranged into a Δ-propeller configuration in all the three CPs. The same chiral type of the space group and the same chiral type of the propellers should be determined by the same chiral type of the L ligands. In addition, the slightly soluble powders of 1 and 2 displayed probe functions of detecting cysteine, glutathione and N-acetyl cysteine in UV–Vis spectrophotometric analysis of suspensions, which extended the application of UV–Vis spectrophotometry into suspension systems of micron particles.

Design, synthesis and biological evaluation of acridone glycosides as selective BChE inhibitors

Based on structure analyses of butyrylcholinesterase (BChE), a series of 21 acridone glycosides were designed, synthesized and evaluated in vitro for their BChE and acetylcholinesterase (AChE) inhibitory activities. d-ribose derivative 6f exhibited the greatest inhibitory activity on BChE (IC50 = 6.95 μM), and was the most selective inhibitor of BChE with the IC50 ratio of AChE/BChE was 20.59. d-glucose and d-galactose derivatives 6a and 6b showed inhibitory activities against both AChE and BChE. Moreover, compounds 6a, 6b, 6f and 5t were found nontoxic on SHSY5Y neuroblastoma and HepG2 cell and exhibited remarkable neuroprotective activity. Besides, compound 6f showed mixed-type inhibition against BChE (Ki = 1.76 μM), which renders 6f a potential agent for the treatment of Alzheimer's disease. These novel acridone hybrids might be used as efficient probes to reveal the relationship between ligands and BChE and pave the way for developing selective BChE inhibitors to further study the pathogenesis of alzheimer's disease.

Design, synthesis, cholinesterase inhibition and molecular modelling study of novel tacrine hybrids with carbohydrate derivatives.

A series of hybrids containing tacrine linked to carbohydrate-based moieties, such as d-xylose, d-ribose, and d-galactose derivatives, were synthesized by the nucleophilic substitution between 9-aminoalkylamino-1,2,3,4-tetrahydroacridines and the corresponding sugar-based tosylates. All compounds were found to be potent inhibitors of both acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) in the nanomolar IC50 scale. Most of the d-xylose derivatives (6a-e) were selective for AChE and the compound 6e (IC50 = 2.2 nM for AChE and 4.93 nM for BuChE) was the most active compound for both enzymes. The d-galactose derivative 8a was the most selective for AChE exhibiting an IC50 ratio of 7.6 for AChE over BuChE. Only two compounds showed a preference for BuChE, namely 7a (d-ribose derivative) and 6b (d-xylose derivative). Molecular docking studies indicated that the inhibitors are capable of interacting with the entire binding cavity and the main contribution of the linker is to enable the most favorable positioning of the two moieties with CAS, PAS, and hydrophobic pocket to provide optimal interactions with the binding cavity. This finding is reinforced by the fact that there is no linear correlation between the linker size and the observed binding affinities. The majority of the new hybrids synthesized in this work do not violate the Lipinski's rule-of-five according to FAF-Drugs4, and do not demonstrated predicted hepatotoxicity according ProTox-II.

Facile Preparation of N-Glycosylated 10-Piperazinyl Artemisinin Derivatives and Evaluation of Their Antimalarial and Cytotoxic Activities.

According to the precepts that C-10 amino-artemisinins display optimum biological activities for the artemisinin drug class, and that attachment of a sugar enhances specificity of drug delivery, polarity and solubility so as to attenuate toxicity, we assessed the effects of attaching sugars to N-4 of the dihydroartemisinin (DHA)-piperazine derivative prepared in one step from DHA and piperazine. N-Glycosylated DHA-piperazine derivatives were obtained according to the Kotchetkov reaction by heating the DHA-piperazine with the sugar in a polar solvent. Structure of the D-glucose derivative is secured by X-ray crystallography. The D-galactose, L-rhamnose and D-xylose derivatives displayed IC50 values of 0.58–0.87 nM against different strains of Plasmodium falciparum (Pf) and selectivity indices (SI) >195, on average, with respect to the mouse fibroblast WEHI-164 cell line. These activities are higher than those of the amino-artemisinin, artemisone (IC50 0.9–1.1 nM). Notably, the D-glucose, D-maltose and D-ribose derivatives were the most active against the myelogenous leukemia K562 cell line with IC50 values of 0.78–0.87 µM and SI > 380 with respect to the human dermal fibroblasts (HDF). In comparison, artemisone has an IC50 of 0.26 µM, and a SI of 88 with the same cell lines. Overall, the N-glycosylated DHA-piperazine derivatives display antimalarial activities that are greatly superior to O-glycosides previously obtained from DHA.

Total Synthesis of Resiniferatoxin Enabled by Radical-Mediated Three-Component Coupling and 7-endo Cyclization.

Resiniferatoxin (1) belongs to a daphnane diterpenoid family and has strong agonistic effects on TRPV1, a transducer of noxious temperature and chemical stimuli. The densely oxygenated trans-fused 5/7/6-tricarbocycle (ABC-ring) of 1 presents a daunting challenge for chemical synthesis. Here we report the development of a novel radical-based strategy for assembling 1 from three components: A-ring 9, allyl stannane 18b, and C-ring 17b. The 6-membered 17b, prepared from d-ribose derivative 19, was designed to possess the caged orthoester structure with α-alkoxy selenide as a radical precursor. Upon treatment of 17b with 18b, 9, and V-40, the potently reactive α-alkoxy bridgehead radical was generated from 17b and then sequentially coupled with 9 and 18b to yield 16b. This first radical reaction formed the hindered C9,10-linkage between the A and C-rings and extended the C4-chain on the A-ring in a stereoselective fashion. After derivatization of 16b into 15, the remaining 7-membered B-ring was cyclized in the presence of n-Bu3SnH and V-40 by utilizing the xanthate on the C-ring as the radical precursor and the allylic dithiocarbonate as the terminator. The second radical reaction thus enabled not only the 7-endo cyclization but also construction of the C8-stereocenter and the C6-exo olefin. Tricycle 14 was elaborated into the targeted 1 by a series of highly optimized chemoselective reactions. The present total synthesis of 1 demonstrates the advantages of radical reactions for linking hindered bonds within carbocycles without damaging preexisting functionalities, thereby offering a new strategic design for multistep target-oriented synthesis.

1,2,4-Triazole d-ribose derivatives: Design, synthesis and antitumoral evaluation

Herein we report the design, synthesis and characterization of novel 1,2,4-triazole d-ribose derivatives, as well as their synthetic precursors. The antitumoral activity against T cell lymphoma cell line of these products was studied. Structures containing a 1,2,4-triazolic ring linked by sulfur to the carbohydrate moiety showed a moderate antiproliferative activity. The presence of the second heterocyclic ring did not show significant changes in their biological activity. Meanwhile, structures with 3-thiobenzyl-5-substituted-1,2,4-triazole ring linked by nitrogen leads to compounds with a biphasic behavior, stimulating cell proliferation at low concentrations and inhibiting it at higher ones. An increment in the polarity was associated with a decrease in the activity of the evaluated compounds. A preliminary antitumoral screening pointed the 1,2,4-triazolic structures linked to protected sugars as promising leaders for further studies.

Preparation of nucleosides derived from 2-nitroimidazole and D-arabinose, D-ribose, and D-galactose by the Vorbrüggen method and their conversion to potential precursors for tracers to image hypoxia.

2-Nitroimidazole was silylated using hexaethyldisilazane and then reacted with 1-O-acetyl derivatives of d-arabinose, d-ribose, and d-galactose in acetonitrile at mild temperatures (−20 °C to rt), catalyzed by triethylsilyl triflate (Vorbrüggen conditions). The α-anomer was formed in the former case and the β-anomers in the latter two cases (highly) selectively. When d-arabinose and d-ribose were silylated with tert-butyldiphenylsilyl chloride in pyridine at the hydroxyl groups at C-5 and acetylated at the other ones in a one-pot reaction, mixtures of anomeric 1-O-acetyl derivatives were obtained. These were coupled by the Vorbrüggen method and then deblocked at C-5 and tosylated to give precursors for tracers to image hypoxia in four steps without using Hg(CN)2 necessary for other methods. The Vorbrüggen conditions enable a shorter route to azomycin nucleoside analogues than the previous coupling procedures.

Spirohydantoins from D-ribose as new potent enzymatic inhibitors.

Anomeric spirohydantoin derivatives from monosaccharides are known for various biological properties. We describe herein the synthesis of the 3-spirohydantoin derivatives of D-allose and D-ribose. The key step is the stereoselective glyco-alpha-aminonitrile formation from ulose derivatives of D-glucose and D-xylose using titanium tetra-isopropoxide as a mild and efficient catalyst. Target compounds were synthesized from these intermediates. The glucidic moiety was partially or totally deprotected under acidic conditions. These new heterocyclic monosaccharidic derivatives are potent glycogen phosphorylase inhibitors.

A short alternative preparation of the bengazoles polyol side-chain segment

A new short and efficient synthesis of the bengazoles side chain is reported using a sequential Grignard addition–hydroboration approach on a readily available d-ribose derivative.

Chemical investigations in the synthesis of O-serinyl aminoribosides

Glycosylation involving d-ribose derivatives and various N-protected tert-butyl l-serinates can be achieved efficiently by careful choice of the activation method at the anomeric position and of the Lewis acid promoter. The conditions described allow the major formation of the β-anomer required for further elaboration to liposidomycin and caprazamycin analogues.

The EPR pattern of Cr V complexes of d-ribose derivatives

Adenosine 5′-monophosphate, cytidine 5′-monophosphate, adenosine and methyl β- d-ribofuranoside form stable Cr V bischelates with the metal bound to the 2,3- cis-diolato moiety of the ribose ring. The EPR spectra of Cr V complexes of these ligands – with the substituent at C1 anti to the 2,3-diolato donor site – possess a common pattern: one quintet at g iso = 1.9803 and one quartet at g iso = 1.9798/7, corresponding to the two geometric isomers of [Cr V(O)( O 2, O 3-ligand] −. The EPR spectra of Cr V bischelates of methyl α- d-ribofuranoside, with the methoxy group at C1 syn to the 2,3-diolato donor site, show a distinct pattern: two quintets at g iso = 1.9793 and 1.9791. This different EPR pattern can be used as an easy way to distinguish between Cr V complexes formed with α- and β-1-substituted d-ribose derivatives.

Efficient synthesis of an adenosine A2a agonist: glycosylation of 2-haloadenines and an N2-alkyl-6-chloroguanine.

A convergent synthesis of adenosine A2a agonist 1 in the form of its maleate salt 2 was achieved. The key step in this approach was the highly selective 9beta-glycosylation reaction between 2-haloadenines or an N(2)-alkyl-6-chloroguanine and a D-ribose derivative containing a 2-ethyltetrazolyl moiety. Glycosylations of other purine derivatives were also examined, and the methods developed provide efficient access to a variety of adenosine analogues such as 2-alkylaminoadenosines, an attractive class of compounds with antiinflammatory activity.

Novel spirohydantoins of d-allose and d-ribose derived from glyco-α-aminonitriles

The synthesis of 3-spirohydantoin derivatives of d-allose and d-ribose is reported. The key step is the stereoselective conversion of glyco-α-aminonitriles from ulose derivatives of d-glucose and d-xylose using titanium(IV) isopropoxide as a mild and efficient catalyst. Cyclisation of the glyco-α-aminonitriles give the target spirohydantoins.

Synthesis of Platinum Complexes from Sugar Derivatives

ABSTRACT Six new platinum(II) complexes containing a diamino sugar, analogs of cisplatin and carboplatin, have been prepared and characterized. The new ligands were obtained by reaction of D-galactose and D-ribose derivatives with ethylenediamine.

Total Synthesis of (+)-Polyoxin J.

Stereoselective total synthesis of (+)-polyoxin J is described. The synthesis was achieved in a convergent manner by coupling protected thymine polyoxin C (19) and 5-O-carbamoyl polyoxamic acid 27 and subsequent removal of the protecting groups. The key steps of the synthesis of protected thymine polyoxin C involved the stereoselective electrophilic epoxidation of E-allyl alcohol 7 derived from isopropylidene D-ribose derivative 5, followed by regioselective epoxide opening of 8 and conversion of resulting azido diol 9 to protected thymine polyoxin C (19). Protected polyoxamic acid 27 was synthesized stereoselectively by utilizing Sharpless epoxidation of tartrate-derived allylic alcohol 20 followed by a regioselective epoxide ring opening with diisopropoxytitanium diazide.

Glucose isomerase catalysed isomerisation reactions of (2 R,3 R)-configured aldofuranoses into the corresponding open-chain 2-ketoses

Immobilised glucose isomerase (EC 5.3.1.5) accepted various (2 R,3 R)-configured aldofuranoses such as d-erythrose, as well as homologous C-5-modified d-ribose derivatives, as substrates. In the case of d-crythrose, quantitative conversion into d- glycero-tetrulose took place. d-Ribofuranoses were converted into the corresponding open-chain 2-ketoses in isolated yields of 65%. Surprisingly, l-crythrose also turned out to be a substrate of this enzyme.

Synthesis of enantiomerically pure bicyclo[3.1.0]hexanes from D-ribose by intramolecular cyclopropanation

Highly functionalized optically pure bicyclo[3.1.0]hexan-2-ones 6a and 6b are easily obtained by the Intramolecular cyclopropanation of a D-ribose derivative using the iodonium ylide or diazo compound methods, which afford the final products with opposite diastereoselectivities.