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At least 19 recordsLinked to original sources
PubMed2002

New cationic olefin cyclization-pinacol reactions. Ring-expanding cyclopentane annulations that directly install useful functionality in the cyclopentane ring.

Two new tandem cationic olefin cyclization-pinacol reactions that provide cyclopentane-fused cycloalkanone products are described. Treatment of cis-1-[2-alkenyl-2-(triethylsiloxy)cycloalkyl]but-3-en-2-ol derivatives 21-24 with triflic anhydride at -78 degrees C affords cycloalkanones 31-34 in 54-90% yields with diastereoselectivities of typically >20:1. In this unusual transformation, the starting cycloalkanone is ring-expanded and fused to a 2-alkenylcyclopentane fragment. Reaction of cis-(2-siloxy-2-alkenylcycloalkyl)pyrrolidin-1-ylethanones 15-17 with triflic anhydride and 2,6-di-tert-butyl-4-methylpyridine (DTBMP) at -20 to +65 degrees C followed by hydrolysis of the intermediate iminium salts 64 with aqueous KHCO(3) affords cycloalkanediones 46-48 in moderate yield and high diastereoselectivity (>20:1). These are the first examples of ring-expanding cyclopentane annulations that directly introduce a carbon side chain or carbonyl functionality at the cyclopentane C2 position. The high diastereoselectivities observed in these reactions are believed to arise from reaction through highly organized cyclic transition states.

Alkenes↗
PubMed1975

Microbial reduction of 1,3-dioxo-2-methyl-2-(3'0oxo-6'-carbomethoxyhexyl)-cyclopentane to form 1 beta-hydroxy-3-oxo-2beta-methyl-2alpha-(3'-oxo-6'-carbomethoxyhexyl)-cyclopentane, an intermediate for steroid total syntheses.

The rate and extent of stereoselective reduction of 1,3-dioxo-2-methyl-2-(3'-oxo-6'-carbomethoxyhexyl)-cyclopentane to form the 1beta-hydroxy-2beta-methyl isomer by cultures of Schizosaccharomyces pombe ATCC 2476 was dramatically increased by addition to the fermentation of certain alpha,beta-unsaturated ketones and allyl alcohol.

Alcohols↗
PubMed1987

Excitation of rat hippocampal neurones by the stereoisomers of cis- and trans-1-amino-1,3-cyclopentane dicarboxylate.

Intracellular recordings were obtained from rat hippocampal neurons during the microiontophoretic ejection of the stereoisomers of cis- and trans-1-amino-1,3-cyclopentane dicarboxylate into the dendritic region (stratum radiatum) of the impaled cells. L-(+)-cis-1-Amino-1,3-cyclopentane dicarboxylate, D(+)-trans-1-amino-1,3-cyclopentane dicarboxylate, and L-(-)-trans-1-amino-1,3-cyclopentane dicarboxylate all evoked patterns of excitation resembling that elicited by kainate. All of these responses were unaffected by D-(-)-2-amino-5-phosphonovalerate but were antagonized at comparable currents by kynurenate. The excitation produced by D-(-)-cis-1-amino-1,3-cyclopentane dicarboxylate was similar to that evoked by N-methyl-D-aspartate. At low ejection currents a slow depolarization triggered rhythmic burst firing, each burst consisting of a depolarizing shift in membrane potential upon which were superimposed four to five action potentials. These responses were antagonized both by D-(-)-2-amino-5-phosphonovalerate and by kynurenate. The results are discussed with respect to the conformational requirements considered to be necessary for interaction at the kainate and N-methyl-D-aspartate receptors on CA1 pyramidal neurones. It is important to note that the isopropylene side chain of kainate is absent from the 1-amino-1-3-cyclopentane dicarboxylate molecule.

Amino Acids↗
PubMed2001

Biosynthetic studies on the cyclopentane ring formation of allosamizoline, an aminocyclitol component of the chitinase inhibitor allosamidin.

Allosamizoline (1) is an aminocyclitol component of allosamidin, a Streptomyces metabolite, and has a cyclopentane ring originated from D-glucosamine. Biosynthesis of the cyclopentane ring was studied by feeding experiments with a variety of deuterium-labeled glucosamine and glucose. In the feeding experiments with [3-(2)H]- and [4-(2)H]-D-glucosamine and [1-(2)H]-D-glucose, deuterium was incorporated into C-3, C-4, and C-1 of 1, respectively. On the other hand, feeding experiments with [5-(2)H]- and [6,6-(2)H(2)]-D-glucosamine showed that deuterium on C-5 and one of the two deuterium atoms on C-6 of glucosamine were lost during the cyclopentane ring formation of 1. In the feeding experiments with (6R)- and (6S)-[6-(2)H(1)]-D-glucose, the (6R)-deuterium of glucose was incorporated into the proS position on C-6 of 1, but the (6S)-deuterium of glucose was not incorporated into 1. These results suggested that an intermediate with a 6-aldehyde group is involved in the biosynthesis of the cyclopentane ring moiety of 1 and overall inversion of stereochemistry of the C-6 methylene group occurred by stereospecific oxidation and reduction on C-6 during the formation of 1. The 6-aldehyde intermediate may play a key role in the biosynthetic step(s) of cyclization to form the cyclopentane ring and/or deoxygenation at C-5.

Acetylglucosamine↗
PubMed1996

Chiral Cyclopentane-Based Mimics of D-myo-Inositol 1,4,5-Trisphosphate from D-Glucose.

Two routes from D-glucose to chiral, ring-contracted analogs of the second messenger D-myo-inositol 1,4,5-trisphosphate are described. Methyl alpha-D-glucopyranoside was converted by an improved procedure into methyl 4,6-O-(p-methoxybenzylidene)-alpha-D-glucopyranoside (6) and thence into methyl 2-O-benzyl-3,4-bis-O-(p-methoxybenzyl)-alpha-D-gluco-hexodialdopyranoside (1,5) (14) in four steps. In the first ring-contraction method 14 was converted into methyl 2-O-benzyl-6,7-dideoxy-3,4-bis-O-(p-methoxybenzyl)-alpha-D-gluco-hept-6-enopyranoside (1,5) (15), which on sequential treatment with Cp(2)Zr(n-Bu)(2) followed by BF(3).Et(2)O afforded a mixture of (1R,2S,3S,4R,5S)-3-(benzyloxy)-4-hydroxy-1,2-bis[(p-methoxybenzyl)oxy]-5-vinylcyclopentane (16) and its 4S,5R diastereoisomer 17. Removal of the p-methoxybenzyl groups of 16 and subsequent phosphorylation and deprotection afforded the first target compound, (1R,2R,3S,4R,5S)-3-hydroxy-1,2,4-tris(phosphonooxy)-5-vinylcyclopentane (3). In the second route, intermediate 14 was subjected to SmI(2)-mediated ring contraction to give (1R,2S,3S,4R,5S)-3-(benzyloxy)-4-hydroxy-5-(hydroxymethyl)-1,2-bis[(p-methoxybenzyl)oxy]cyclopentane (20). Benzylation of 20 provided (1R,2S,3S,4R,5S)-3-(benzyloxy)-6-[(benzyloxy)methyl]-4-hydroxy-1,2-bis[(p-methoxybenzyl)oxy]cyclopentane (22) and (1R,2S,3S,4R,5S)-3,4-bis(benzyloxy)-5-(hydroxymethyl)-1,2-bis[(p-methoxybenzyl)oxy]cyclopentane (21), which were elaborated to the target trisphosphates (1R,2R,3S,4R,5S)-3-hydroxy-5-(hydroxymethyl)-1,2,4-tris(phosphonooxy)cyclopentane (4) and (1R,2S,3R,4R,5S)-1,2-dihydroxy-3,4-bis(phosphonooxy)-5-[(phosphonooxy)methyl]cyclopentane (5), respectively. Both 3 and 4 mobilized intracellular Ca(2+), but 4 was only a few fold less potent than D-myo-inositol 1,4,5-trisphosphate, demonstrating that effective mimics can be designed that do not bear a six-membered ring.

Journal Article↗
PubMed1991

Synthesis of optically pure di- to tetra-substituted cyclopentanes from sugar-derived norbornene derivatives.

The chiral norbornene derivative 2 obtained from Lewis acid-catalyzed reaction of an L-arabinose-derived dienophile 1 and cyclopentadiene was oxidized with OsO4-NaIO4 to the dialdehyde 3, a tetrasubstituted cyclopentane. Mild treatment of 3 with [Rh(dppp)2]Cl [dppp = Ph2P(CH2)3PPh2] (4) selectively epimerized the aldehyde adjacent to the methoxycarbonyl group to give the epi-aldehyde 8. Under more vigorous conditions, this group was decarbonylated to give the monoaldehyde 11, and more strenuous treatment removed the second aldehyde group to give the didecarbonylated cyclopentane derivative 5. The structure and optical purity of 5 was confirmed by its transformation into (1S,2S)-cyclopentane-1,2-dicarboxylic acid (7).

Carbohydrates↗
PubMed2004

Synthesis and supramolecular assemblies of bipolar archaeal glycolipid analogues containing a cis-1,3-disubstituted cyclopentane ring.

Unsymmetrical archaeal tetraether glycolipid analogues 1-2 incorporating a 1,3-disubstituted cyclopentane ring into the bridging chain have been synthesized. The cyclopentane has been introduced with a totally controlled cis configuration, either into the middle of the aliphatic chain or at three methylene groups from the glycerol unit linked to the bulkier disaccharide residue. Freeze-fracture and cryotransmission electron microscopy experiments clearly demonstrated unprecedented glycolipid supramolecular organizations involving two-by-two monolayer associations coupled with interconnection and fusion phenomena. Furthermore, a significant difference in the hydration properties and in the lyotropic liquid crystalline behavior of bipolar lipids 1-2 was found depending on the position of the cyclopentane residue.

Archaea↗
PubMed2003

A cyclopentane conformational restraint for a peptide nucleic acid: design, asymmetric synthesis, and improved binding affinity to DNA and RNA.

[structure: see text] A strategy to restrict the highly flexible backbone conformation of a peptide nucleic acid (PNA) by incorporation of a cyclopentane ring is proposed. An asymmetric synthesis of cyclopentane-modified PNA is reported, and its binding properties were determined. The cyclopentane ring leads to a significant improvement in the binding properties of the resulting PNA to DNA and RNA.

Alkylation↗
PubMed1999

Synthesis of Enantio- and Diastereomerically Pure, Tetra- and Penta-Substituted Cyclopentanes by the Desymmetrization of endo-Norborn-5-ene-2,3-dicarboxylic Anhydrides.

The desymmetrization of endo-norborn-5-ene-2,3-dicarboxylic anhydrides by methyl (S)-prolinate followed by ozonolysis of the resulting carboxylic acids is used to prepare enantio- and diastereomerically pure, tetra- and penta-substituted cyclopentane derivatives in which all of the substituents on the cyclopentane ring are syn to one another. The initial products of this chemistry (2a,b and 18a,b) contain two aldehyde groups, one of which exists as a hemiacetal. This allows subsequent chemistry to be carried out regioselectively at one of the two aldehyde groups. Hence, the sodium borohydride reduction of hemiacetals 2a,b can be controlled to give either a bicyclo[3.2.1] (4) or bicyclo[3.3.0] lactone (5) as the product. The addition of allylindium to hemiacetals 2a,b occurs both regio- and diastereoselectively to give polycyclic acetal 12, the stereochemistry of which is consistent with a chelation controlled addition. It is possible to remove the proline ester based auxiliary from the cyclopentane derivatives by gamma-lactone formation under mild reaction conditions.

Journal Article↗
PubMed1983

Chiral synthesis of asymmetrically tetra-C-substituted cyclopentane derivatives by Diels-Alder addition of cyclopentadiene to unsaturated acyclic-sugar derivatives.

Optically pure, substituted cyclopentane derivatives of interest in synthesis of prostaglandin analogs have been obtained by stereocontrolled addition of cyclopentadiene to trans alpha,beta-unsaturated sugar derivatives. Methyl (E)-4,5,6,7-tetra-O-acetyl-2,3-dideoxy-D-arabino-hept-2-enonate (2), obtained by Wittig addition of Ph3PCHCO2Me to aldehydo-D-arabinose tetraacetate, reacted with cyclopentadiene in boiling toluene to give 40% of a crystalline, norbornene adduct (3) having the 5S-exo ester, 6S-endo sugar-chain configuration, as established by crystallography and by conversions into the known, crystalline (2S,3S)-bis(p-tolylsulfonyloxymethyl)bicyclo[2.2.1]heptane. Likewise, the L enantiomer (19) of 2 was converted into the crystalline enantiomer of 3; chromatographic resolution of the other Diels-Alder adducts from the reaction afforded lesser amounts of the other three possible isomeric adducts, which were characterized by appropriate conversions. The Ph3PCHCO2Me Wittig adduct (9) from 2,3:4,5-di-O-isopropylidene-aldehydo-D-arabinose with cyclopentadiene in hot toluene gave a crystalline mixture of the isomeric 5S,6S adducts (10 and 11), separable after deacetonation and acetylation as the already characterized product 3 and its 6S-endo ester, 5S-exo sugar-chain isomer. Likewise, the L enantiomer of the D dienophile 9 gave a crystalline mixture of 5R,6R adducts that were the enantiomers of 10 and 11. A reversed ratio of adducts resulted when the tetraacetylated L dienophile 19 reacted at 0 degrees with cyclopentadiene under AlCl3 catalysis, and 36% of the crystalline 5S-endo ester, 6S-exo sugar-chain adduct (23) was obtained. Hydroxylation-glycol cleavage of the double bond in 23, followed by reduction and acetylation, gave 65% of an optically pure cyclopentane derivative having five chiral centers of the same absolute configuration as in prostaglandin F1 alpha.

Carbohydrates↗
PubMed2005

Comparison of the anti-influenza virus activity of cyclopentane derivatives with oseltamivir and zanamivir in vivo.

Cyclopentane derivatives, designated as BCX-1812, BCX-1827, BCX-1898, and BCX-1923, were tested in parallel with oseltamivir carboxylate and zanamivir for the in vivo activity in mice infected with A/Turkey/Mas/76 X A/Beijing/32/92 (H6N2) influenza virus. The compounds were tested orally and intranasally at different dose levels. BCX-1812, BCX-1827, and BCX-1923 showed more than 50% protection at 1mg/kg/day dose level on oral treatment. The intranasal treatment was 100% effective even at 0.01 mg/kg/day for all four compounds. On comparison with oseltamivir carboxylate and zanamivir, these four cyclopentane derivatives have shown equal or better efficacies. The synthesis of two new compounds, BCX-1898 and BCX-1923, is also described.

Acetamides↗
PubMed2005

Total synthesis and antiangiogenic activity of cyclopentane analogues of fumagillol.

Novel cyclopentane analogues of fumagillol were synthesized and their endothelial cell proliferation inhibitory activities were evaluated. The cyclopentane-fumagillol derivatives were synthesized from (-)-2,3-O-isopropylidene-D-erythronolactone via stereoselective glycolate Claisen rearrangement and intramolecular ester enolate alkylation as key steps.

Alkenes↗
PubMed2006

Cyclopentane-based human NK1 antagonists. Part 1: discovery and initial SAR.

An initial investigation of the novel cyclopentane scaffold 6 afforded low nanomolar human NK1 antagonists having enhanced water solubility properties compared to morpholine 1. A synthesis of this cyclopentane scaffold, having three contiguous chiral centers, and the unexpected determination that the 1,2-trans-2,3-trans-ring stereochemistry, as opposed to the cis-ether/phenyl configuration of the known structures 1-5, is optimal for this class of antagonist are described.

Cyclopentanes↗
PubMed2006

Peptide nucleic acid microarrays made with (S,S)-trans-cyclopentane-constrained peptide nucleic acids.

Procedures to attach trans-cyclopentane-modified peptide nucleic acid oligomers to a glass slide are described. Peptide nucleic acids can offer distinct advantages to DNA detection compared to typically used DNA microarrays, especially with regard to chemical stability and quality of data. The trans-cyclopentane modification incorporated into the peptide nucleic acid is, in some cases, essential for successful DNA detection. It is hoped that these peptide nucleic acid-bearing glass slides will find application in several areas of DNA microarray technology.

Cyclopentanes↗
PubMed2004

(S,S)-trans-cyclopentane-constrained peptide nucleic acids. a general backbone modification that improves binding affinity and sequence specificity.

Replacing the ethylenediamine portion of aminoethylglycine peptide nucleic acids (aegPNAs) with one or more (S,S)-trans-cyclopentane diamine units significantly increases binding affinity and sequence specificity to complementary DNA, making these modified PNAs ideal for use as nucleic acid probes in genomic analysis. The synthesis and study of this new class of PNAs (tcypPNAs) is described in which trans-cyclopentane diamine has been incorporated into several positions, and in varying number, within PNA backbones of mixed-base sequences.

Base Pair Mismatch↗
PubMed2003

Synthesis of cyclopentane amide DNA (cpa-DNA) and its pairing properties.

We recently reported on the synthesis and pairing properties of the DNA analogue bicyclo[3.2.1]amide DNA (bca-DNA). In this analogue the nucleobases are attached via a linear, 4-bond amide-linker to a structurally preorganized sugar-phosphate backbone unit. To define the importance of the degree of structural rigidity of the bca-backbone unit on the pairing properties, we designed the structurally simpler cyclopentane amide DNA (cpa-DNA), in which the bicyclo[3.2.1]-scaffold was reduced to a cyclopentane unit while the base-linker was left unchanged. Here we present a synthetic route to the enantiomerically pure cpa-DNA monomers and the corresponding phosphoramidites containing the bases A and T, starting from a known, achiral precursor in 9 and 12 steps, respectively. Fully modified oligodeoxynucleotides were synthesized by standard solid-phase oligonucleotide chemistry, and their base-pairing properties with complementary oligonucleotides of the DNA-, RNA-, bca-DNA-, and cpa-DNA-backbones were assessed by UV melting curves and CD-spectroscopic methods. We found that cpa-oligoadenylates form duplexes with complementary DNA that are less stable by -2.7 degrees C/mod. compared to DNA. The corresponding cpa-oligothymidylates do not participate in complementary base-pairing with any of the investigated backbone systems except with its own (homo-duplex). As its congener bca-DNA, cpa-DNA seems to prefer left-handed helical duplex structures with DNA or with itself as indicated by the CD spectra.

Amides↗
PubMed2000

An unusual samarium diiodide mediated reductive ring contraction of a tricyclic oxazine to a highly-functionalized cyclopentane and cyclobutane.

[reaction--see text] Samarium diiodide mediated reductive ring contraction of a substituted tricyclo[2.2.2]oxazine at 25 degrees C leads to a mixture of cyclopentane and cyclobutane rearrangement products with complete diastereoselectivity in each case. At -78 degrees C, the anticipated amidocyclohexanol reduction product is obtained exclusively, while the cyclopentane is the sole product at reflux in THF.

Cyclobutanes↗