Cyclopentanone Ring Research Articles

(2E,5E)-2,5-Difurfurylidenecyclopentanone

In the title mol­ecule, C15H12O3, the three five-membered rings are nearly coplanar: the dihedral angles between the cyclopentanone ring and the furan rings are 3.5 (2) and 9.7 (2)°, and the two furan rings form a dihedral angle of 7.2 (2)°. In the crystal structure, weak inter­molecular C—H⋯O hydrogen bonds help to consolidate the crystal packing.

Probing the structure and Franck–Condon region of protochlorophyllide a through analysis of the Raman and resonance Raman spectra

AbstractThe structure and Franck–Condon region of protochlorophyllide a, a precursor in the biosynthesis of chlorophyll and substrate of the light‐regulated enzyme protochlorophyllide oxidoreductase (POR), were investigated by Raman and resonance Raman (RR) spectroscopy. The spectroscopic results are compared to the spectra of the structurally closely related porphyrin model compound magnesium octaethylporphyrin (MgOEP), and interpreted on the basis of density functional theory (DFT) calculations. It is shown that the electronic properties of the two porphyrin macrocycles are affected by different vibrational coupling modes, resulting in a higher absorption cross section of protochlorophyllide a in the visible spectral region. Furthermore, a comparison of the Fourier transform (FT)‐Raman and RR spectra of protochlorophyllide a indicates the modes that are resonantly enhanced upon excitation. Based on vibrational normal mode calculations, these modes include CC ring‐breathing and CC stretching vibrations of the porphyrin macrocycle. In particular, the strong band at 1703 cm−1 can be attributed to the CO carbonyl vibration of the cyclopentanone ring, which is attached in conjugation to the π‐electron path of the porphyrin ring system. The enhancement of that mode upon electronically resonant excitation is discussed in the light of the reaction model suggested for the photoreduction of protochlorophyllide a in the POR. Copyright © 2009 John Wiley & Sons, Ltd.

Methyl 5-ferrocenyl-5a-hydroxy-1-methyl-10-oxo-2,3,3a,4,5a,10-hexahydro-1H-indeno[1,2:2′,3′]furo[3′,4′-b]pyrrole-3a-carboxylate

In the title compound, [Fe(C5H5)(C21H20NO5)], the pyrrolidine and cyclo­penta­none rings exhibit a twist conformation. The pyrrolidine ring is almost perpendicular to the cyclo­penta­none ring, making a dihedral angle of 81.91 (6)°. The mol­ecular conformation is stabilized by an intra­molecular O—H⋯N hydrogen bond and C—H⋯O inter­actions. The crystal structure is stabilized by inter­molecular C—H⋯O inter­actions.

Identification of degradation products in loxoprofen sodium adhesive tapes by liquid chromatography–mass spectrometry and dynamic pressurized liquid extraction–solid-phase extraction coupled to liquid chromatography–nuclear magnetic resonance spectroscopy

Rapid and unambiguous identification of three degradation products (DP-1, DP-2 and DP-3) found in heat-stressed loxoprofen sodium adhesive tapes (Loxonin tapes) was achieved by LC–MS and dynamic pressurized liquid extraction (PLE)–solid-phase extraction (SPE) coupled to LC–NMR without complicated isolation or purification processes. The molecular formulae of the degradation products were determined by accurate mass measurements and product ion analyses and on-line hydrogen/deuterium (H/D) exchange experiments provided information about changes in the degradation of loxoprofen. To compensate for the low sensitivity of NMR, on-line dynamic PLE–SPE was employed and higher concentrations of degradation products trapped on the SPE column were afforded in a shorter time than they would be in such time-consuming sample preparations as pre-concentration after extraction. The loop-storage procedure was used in the LC–NMR analysis to allow the acquisition of the 1H spectra of the three degradation products in one chromatographic run without affecting the peak separation and to avoid the carry-over of previously eluted DP-1 of high concentration by washing the NMR detection cell prior to the measurement of the DP-2 spectrum. Based on the resulting 1H NMR spectra in combination with the MS results, DP-1 was successfully identified as an oxidation product having an oxodicarboxylic acid structure formed by the cleavage of the cyclopentanone ring of loxoprofen, DP-2 as a cyclopentanone ring-hydroxylated loxoprofen and DP-3 as a loxoprofen l-menthol ester.

Methyl 2-hydroxy-3-(2-nitrophenyl)-2-(2-oxocyclopentyl)propanoate

In the title compound, C15H17NO6, the nitro group is tilted at a dihedral angle of 44.1 (3)° with respect to the benzene ring. The five-membered cyclopentanone ring adopts an envelope conformation. Intra­molecular O—H⋯O hydrogen bonding is observed.

Cyclopentanone Ring Expansion Leading to Functionalized δ‐Lactams: Short Synthesis of Simple Sedum Alkaloids.

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Synthesis and evaluation of novel pyrazolidinone analogs of PGE 2 as EP 2 and EP 4 receptors agonists

Replacement of the hydroxy cyclopentanone ring in PGE 2 with chemically more stable heterocyclic rings and substitution of the unsaturated α-alkenyl chain with a metabolically more stable phenethyl chain led to the development of potent and selective analogs of PGE 2. Compound 10f showed the highest potency and selectivity for EP 4 the receptor.

2,5-Bis(3,4-dimethoxybenzylidene)cyclopentanone

The title compound, C23H24O5, a bis(3,4-dimethoxyphenyl)cyclopentanone derivative related to curcumin, shows noncrystallographic C-2v symmetry with two noncrystallographic mirror planes intersecting the cyclopentanone ring, resulting in a noncrystallographic twofold axis along the C = O double bond. The molecule is basically planar, the angles between the planes of the cyclopentanone ring and those of the two benzene rings being 2.5 (3) and 1.2 (7)degrees. The dihedral angles of both methoxy groups with the benzene rings are nearly identical 179.05 (11), 177.88 (11), -172.51 (12) and 176.11 (13)degrees]. The two 3,4-dimethoxyphenyl groups also lie within the plane of the molecule and the angle between them is 1.4 (1)degrees. The crystal packing is stabilized by intermolecular C-H center dot center dot center dot O hydrogen bonds.

Cyclopentanone Ring Expansion Leading to Functionalized δ-Lactams: Short Synthesis of Simple Sedum Alkaloids

Monosubstituted epoxides react with (cyclopentenyloxy)trimethylsilane to afford, after subsequent oxidative fragmentation, a pair of diastereomeric 8-membered iodolactones. When these lactones are separately treated with sodium azide, followed by reduction over Lindlar's catalyst, lactone ring contraction yields 6-membered monosubstituted lactams. When (R)-1,2-epoxypentane is used in this 5 + 3 - 2 overall ring expansion sequence, one final step involving delta-lactam to piperidine reduction yields natural (-)-halosaline and (-)-epihalosaline in five steps and 12% and 23% overall yields, respectively.

Dicobaltoctacarbonyl-Mediated Synthesis of Tricyclic 5,6-Diydropyran-2-one Derivatives via Tandem Cycloaddition Reaction between cis-Epoxyalkynes, a Tethered Olefin, and Carbon Monoxide

Cobalt carbonyl complex Co2(CO)8 implemented an intramolecular carbonylation of cis-epoxyalkynes to generate Co2(CO)6-stabilized gamma-lactonyl allene species. For 1,1,2-trisubstituted epoxyalkynes, this Co2(CO)6-allene species reacted with a tethered olefin to give [2+2]-cycloadducts, and with CO and a tethered olefin to produce [2+2+1]-cycloadducts. These resulting cycloadducts have a 5,6-diydropyran-2-one core fused with a cyclobutane and a cyclopentanone ring, respectively. For 1,2-disubstituted cis-epoxyalkyne and 1,1,2-trisubstituted cis-epoxyalkynes bearing a heteroatom constituent, cyclization of the corresponding epoxyalkyne with a tethered alkene is invariably accompanied by incorporation of CO to produce a [2+2+1]-cycloadduct, even in the absence of CO. We have prepared various 1,1,2-trisubstituted and 1,2-disubstituted cis-epoxyalkynes to generalize such cycloaddition pathways. Attempt to use an organic promoter to perform these tandem cycloadditions was unsuccessful because of a competing Pauson-Khand reaction. Cyclization of a 1,2-disubstituted epoxyalkyne with a tethered diene was achieved successfully in one case, but the yield was low (25%).

Fluorescent properties and spontaneous Raman spectroscopy of new ketocyanine probes in organic solvents

We have used fluorescence spectroscopy and spontaneous Raman spectroscopy to study the characteristics of two ketocyanine dyes: 2,5-di[(E)-1-(4-diethylaminophenyl)methylidene]-1-cyclopentanone (CPET) and 2-[(E)-1-(4-diethylaminophenyl)methylidene]-5-{(E)-1-[4-(4,7,10,13-tetraoxa-1-azacyclopentadecalin) phenyl]methylidene}-1-cyclopentanone (CPMR) in organic solvents. The position of their electronic spectra depends strongly on the polarity of the solvent. We measured the dipole moments of the dyes in the equilibrium ground state and the Franck-Condon excited state. In mixtures of neutral nonpolar toluene with aprotic polar dimethylsulfoxide, we observe inhomogeneous broadening of the electronic spectra for the indicated compounds, due to fluctuations in solution of the intermolecular interaction energy. The time-resolved characteristics of fluorescence obtained suggest formation of an intermolecular hydrogen bond between the dye and the surrounding medium in a toluene-ethanol mixture. We measured the Raman spectra of CPET and CPMR in different organic solvents. The most intense lines in the 1582–1591 cm−1 region can be assigned to stretching of the phenyl rings of the molecules; the lines in the 831–842 cm−1 region can be assigned to a cyclopentanone ring mode; the lines at 1186–1195 cm−1 can be assigned to stretching of the =C-C-bond of the phenyl ring and rocking of the H atoms of the phenyl ring. We have observed that the position and width of the lines for the stretching vibrations of the ketocyanines depend substantially on the polarity of the surrounding medium. The studied dyes can be used as probes for studying different biological systems by site-selective laser spectroscopy and Raman spectroscopy. The fact that these two methods can be used simultaneously for diagnostics of biosystems is an important advantage of ketocyanine dyes compared with other known probes.

Green Self‐Assembling Porphyrins and Chlorins as Mimics of the Natural Bacteriochlorophylls c, d, and e

AbstractNovel porphyrins and chlorins that self‐assemble in nonpolar solvents in a manner similar to that of the bacteriochlorophylls c, d, and e have been synthesized by a common protective group approach. The supramolecular assemblies have broad and red‐shifted absorption spectra in comparison to those of the monomeric building blocks. The presence of a carbonyl group in conjugation with the tetrapyrrolic macrocycle produces green colors both in the free bases and in their zinc complexes, which, after self‐assembly, are thus perfect artificial mimics of the chlorosomal antennas encountered in green photosynthetic bacteria. Enantiopure building blocks produce large helical aggregates with M or P helicity determined by the chirality of the 1‐hydroxyethyl substituent. It is demonstrated that the groups essential for self‐organization to occur − namely the hydroxy group, the zinc metal atom and the carbonyl group − do not have to be collinear, as has been presumed until now. Surprisingly, the chlorin derivative does not show hyperchromicity relative to similarly substituted porphyrins. This fact allows us to conclude that the more readily available porphyrins may be used for efficient artificial antennas of potential use in solar devices; otherwise it is necessary to increase the number of synthetic steps in order to incorporate into chlorins the annulated cyclopentanone ring, a structural feature carefully optimized by evolution in all (bacterio)chlorophylls. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Discovery and Synthesis of a Potent, Selective and Orally Bioavailable EP4 Receptor Agonist

An optimized analog of prostaglandin E 2 which incorporates a γ-lactam in place of the cyclopentanone ring and which incorporates metabolically stabilized side chains, has been identified and shown to exhibit potent and selective EP4 receptor agonism. The compound (2) (L-000902688) is also well absorbed on oral dosing and exhibits a long half-life making it an excellent tool for the study of the role of EP4 receptor in physiology and disease. An efficient synthesis of 2 from a chiral synthon is described.

Novel Acid‐Catalyzed Rearrangement of Methanofullerenes Bearing an α‐Ylidic Ester to Cyclopentanofullerenes: A Vinyl Cyclopropane‐Type Ring Expansion.

A novel acid-catalyzed ring expansion of methanofullerenes bearing an α-ylidic ester has been investigated. Treatment of dialkyl acetylenedicarboxylate and tricycloalkylphosphine with C60 led to the isolation of a methanofullerene ylide after passing the reaction mixtures through a basic alumina column. If the reaction mixture was passed through a silica gel column, a cyclopentanofullerene was isolated instead. These new cyclopentanofullerenes consisted of a fused cyclopentanone ring bearing an α-hydroxy ester and a phosphonium ylide and were confirmed by their NMR, mass, and X-ray diffraction data. The cyclopentanofullerenes were formed by the ring expansion of the corresponding methanofullerenes in the presence of silica gel. The ring expansion also proceeded by treating methanofullerene with acetic acid in chloroform. On the other hand, the methanofullerenes from RO2CCCCO2R, PAr3, and C60 were stable in silica gel. However, upon heating with acetic acid at 50 °C, they underwent ring expansion and depho...

Novel acid-catalyzed rearrangement of methanofullerenes bearing an alpha-ylidic ester to cyclopentanofullerenes: a vinyl cyclopropane-type ring expansion.

A novel acid-catalyzed ring expansion of methanofullerenes bearing an alpha-ylidic ester has been investigated. Treatment of dialkyl acetylenedicarboxylate and tricycloalkylphosphine with C(60) led to the isolation of a methanofullerene ylide after passing the reaction mixtures through a basic alumina column. If the reaction mixture was passed through a silica gel column, a cyclopentanofullerene was isolated instead. These new cyclopentanofullerenes consisted of a fused cyclopentanone ring bearing an alpha-hydroxy ester and a phosphonium ylide and were confirmed by their NMR, mass, and X-ray diffraction data. The cyclopentanofullerenes were formed by the ring expansion of the corresponding methanofullerenes in the presence of silica gel. The ring expansion also proceeded by treating methanofullerene with acetic acid in chloroform. On the other hand, the methanofullerenes from RO(2)CCCCO(2)R, PAr(3), and C(60) were stable in silica gel. However, upon heating with acetic acid at 50 degrees C, they underwent ring expansion and dephosphination to give cyclopentenofullerenes. An implicit vinyl cyclopropane ring expansion mechanism was proposed to account for this novel acid-catalyzed rearrangement.

Structure–activity relations of substituted, deleted or stereospecifically altered jasmonic acid in gene expression of barley leaves

Abstract Jasmonic acid and 66 structurally related compounds were tested to find the structural requirements which induce the expression of jasmonate-responsive genes in barley. An intact cyclopentanone ring as well as a pentenyl side chain exhibiting only minor alterations are necessary for this activity. The (−)-enantiomeric and the (+)-7- iso -enantiomeric structure increase activity of jasmonoyl compounds.

Palladium (II) catalyzed regioselective lactonization of steroids. Chemoselective construction of novel estrone derivatives

Palladium acetate and 1,4-bis(diphenylphosphino)butane (dppb) catalyze regioselective cyclocarbonylation of 4-allylsteroids forming exclusively 7-membered ring lactones with excellent yields (96–98 %). The stereoselective addition of an epoxide ring on the side-chain of steroids is realized by coupling the carbonyl group of the cyclopentanone ring of the steroid with 2-benzothiazolylchloromethyllithium 1 or 4,4-dimethyl-2-oxazolinylchloroalkylithiums 2 and 3.

The pseudoguaianolide isoconfertiflorin

The sesquiterpene lactone isoconfertiflorin, C17H22O5, 1, crystallizes in trigonal space group P31 with a = 10.4498(5), c = 12.7516(8) A, V = 1205.9(2) A3, and Z = 3. It differs from confertiflorin in having an endocyclic C=C bond in the lactone ring, which carries an exocyclic methyl group. The seven-membered ring adopts an approximate twist-chair conformation with C10 lying in the local two-fold axis, and asymmetry parameter ΔC2 = 5.8°. The cyclopentanone ring has the half-chair conformation with C4 on the local two-fold axis, and ΔC2 = 0.9°. The lactone ring is almost planar with maximum deviation 0.014(2) A. Both methyl groups on the 7-membered ring are β–oriented. The acetyl group at C8 has an α orientation.

Studies toward the total synthesis of antibiotic roseophilin: A novel synthesis of the macrotricyclic part

The macrotricyclic part of roseophilin, a novel cytotoxic antibiotic, was efficiently synthesized starting with the known 3-formylpyrrole; the method features intramolecular alkylation to form the desired thirteenmembered carbocycle and base-induced intramolecular acylation to construct the requisite pyrrole-fused cyclopentanone ring system as the key steps.

(2R,3S)-3-Phenyl-2-[(2S,4S)-4-phenyl-3-tosyl-1,3-oxazolidin-2-yl]cyclopentanone

The stereochemical parameters of the title compound, C27H27NO4S, are in good agreement with other arylsulfonyloxazolidines. Whereas the oxazolidine ring displays a twist conformation, the cyclopentanone ring has an envelope conformation.