bluuebunny/crossref_metadata_2025_split huggingface dataset:
13C NMR spectra of alcohols and corresponding nitrate esters
Authors: Narasimhan S. , Srinivasan S. K. , Venkatasu‐Bramanian N. 
Published: May 2005

AbstractThe 13C NMR spectra of alcohols and their corresponding nitrate esters were investigated. An empirical equation is suggested for the change in the chemical shift due to substitution by a nitro group. The spin‐lattice relaxation times are reported.
Correlation between 77Se and 125Te chemical shifts in related heterocycles
Authors: Baiwir Marcel , Llabrès Gabriel , Christiaens Léon , Evers Michel , Piette Jean‐Louis 
Published: May 2005

AbstractA linear relationship was observed between the 77Se and 125Te chemical shifts in 14 model heterocycles (including 17 new data). The line slope, 1.3, is discussed in terms of Jameson and Gutowski's expression for the Ramsey paramagnetic term, σP. The shifts are also compared with the 17O chemical shifts in related compounds.
Carbon‐13 nuclear magnetic resonance study of the bromo derivatives of 5α‐cholestan‐3‐one and cholest‐4‐en‐3‐one
Authors: Römer Johannes , Scheller Dieter , Grossmann Gisbert 
Published: May 2005

AbstractThe 13C NMR spectra of nineteen bromo derivatives of 5α‐cholestan‐3‐one, cholest‐4‐en‐3‐one and cholest‐5‐en‐3‐one have been recorded. The substituent effects are analysed and examined with respect to additivity. The more interesting γsyn and γanti effects are considered in detail.
185Re and 187Re solid‐state NMR of metaperrhenates
Authors: Klobasa Dagmar G. , Burkert Paul K. 
Published: May 2005

Abstract127I solid‐state NMR investigations of specific metaperiodates with alkyl‐ or aryl‐substituted cations of main Group V revealed second‐order quadrupole effects, except in the case of tetraethylammonium and tetramethylphosphonium metaperiodate. In these compounds the 127I quadrupole interactions are either very small or vanish. This allowed the approximate evaluation of the electric field gradients of the analogous isomorphous metaperrhenates. Despite the very large nuclear quadrupole moments of the rhenium isotopes, the estimated values of the 185Re and 187Re quadrupole coupling constants of tetraethylammonium and tetramethylphosphonium metaperrhenate have an order of magnitude accessible to solid‐state NMR measurements. The 185Re and 187Re NMR powder spectra of rhenium compounds in non‐cubic lattice structures were measured for the first time. The complete 185Re and 187Re solid‐state NMR spectra of polycrystalline tetramethylphosphonium metaperrhenate were observed, showing temperature‐dependent second‐order quadrupole splittings. In this compound the ReO anions show very small deviations from tetrahedral symmetry, which were estimated from a point charge model and the measured quadrupole splittings. In contrast, the tetrahedral symmetry of the ReO ions of tetraethylammonium metaperrhenate is nearly undistorted, because no quadrupole splittings of the 185Re and 187Re signals were detectable in the powder NMR spectrum.
Reverse anomeric effect of the carbamoyl group of 2,6‐disubstituted 6‐carbamoyl‐5,6‐dihydro‐2H‐pyrans
Authors: Chmielewski Marek , Jurczak Janusz , Priebe Waldemar , Horton Derek 
Published: May 2005

AbstractThe 1H NMR spectra of 2,6‐disubstituted 6‐carbamoyl‐5,6‐dihydro‐2H‐pyrans and their 6‐methoxycarbonyl analogs have been recorded. With the use of coupling constants between ring protons, the conformational preference of the carbamoyl group has been evaluated. The 1H6⇌6H1 conformational equilibria in the above compounds are discussed. It is found that the conformational tendency of the carbamoyl group to the equatorial disposition helps to determine the conformational equilibrium in the seven examples studied.
Carbon‐13 NMR spectra of some 4‐substituted phenacyl chlorides and iodides
Authors: Olivato Paulo Roberto , Guerrero Sandra Alvarez , Rittner Roberto 
Published: May 2005

AbstractThe 13 NMR singles for some 4‐substituted phenacylchlorides and iodides were assigned. The carbonyl carbons exhibit upfield shifts compared with those of the corresponding 4‐substituted acetophenones; in the chlorinated derivatives a downfield shift is observed for the α‐methylene carbons, while a reverse effect occurs in the iodinated compounds. The chemical shifts of the aromatic ring carbons are in close agreement with those calculated using substituent chemical shifts.
Structure of nitroguanidine: Nitroamine or nitroimine? New NMR evidence from 15N‐labeled sample and 15N spin coupling constants
Authors: Bulusu S. , Dudley R. L. , Autera J. R. 
Published: May 2005

AbstractThe structure of nitroguanidine was investigated by the application of 15N, 1H and 13C NMR spectroscopy of a fully 15N‐labeled sample in DMSO‐d6 and DMF solutions and by 15N CP/MAS NMR in the solid state. These spectra confirm the nitroimine structure which has been suggested by other investigations in recent years, and do not lend any support to the commonly used nitroamine structure or for a tautomeric equilibrium with the nitroamine. Useful 15N spin coupling constants to the 1H and 13C nuclei in the assigned structure are reported.
Re‐examination of the 13C NMR spectra of synthetic chlorins
Authors: Stolzenberg Alan M. , Stershic Matthew T. 
Published: May 2005

AbstractThe 13C NMR spectra of the synthetic chlorins H2(OEC), Ni(TMC) and H2(TPC) have been re‐examined. Evidence from single‐frequency proton decoupled, proton coupled, and 2D 13C‐13C INADEQUATE experiments show that the previous assignments of the meso‐substituted chlorins were incorrect. Corrected assignments establish that the α‐pyrroline carbons of chlorins occur at lower fields (150–175 ppm) than the α‐pyrrole carbons.
13C NMR study of polyphenyl‐, poly‐N‐azolyl‐and poly‐N‐benzazoyl‐methanes
Authors: Elguero J. , Claramunt R. M. , Garcerán R. , Julià S. , Avila L. , del Mazo J. M. 
Published: May 2005

Abstract13C NMR chemical shifts of 69 substituted methanes (general formula R1R2R3R4C, where the substituents were H, C6H5, Cl, OH, OR, imidazol‐1‐yl, pyrazol‐1‐yl, 1,2,4‐triazol‐1‐yl, 1,2,4‐triazol‐4‐yl, benzimidazol‐1‐yl, indazol‐1‐yl, indazol‐2‐yl, benzotriazol‐1‐yl and benzotriazol‐2‐yl) are reported. The effects of the various N‐substituents on the 13C chemical shifts of the heterocyclic nuclei are reported. The chemical shifts of the methane carbon atom are discussed using an interactive model. Some 1H‐13C coupling constants have been measured.
Asymmetry parameters of the electric field gradient at the nuclei in compounds of the RC6H4COCl series
Authors: Feshin V. P. , Dolgushin G. V. , Voronkov M. G. , Sapozhnikov Yu. E. , Yasman Ya. B. 
Published: May 2005

AbstractAsymmetry parameters of the electric field gradients at the 35Cl nuclei in compounds of the RC6H4COCl series (R = H, 4‐CH3, 2‐, 3‐ and 4‐COCl) have been measured at 77 K. They indicate a high asymmetry (> 20%) of the chlorine electron distribution in all the molecules studied. The substituent R in the aromatic ring has no significant effect on the asymmetry.
Relaxation processes in aromatic methly groups. II—Methyl hydrogen T1 values for some halo‐toluenes and ‐xylenes
Authors: Rae Ian D. , Sandbach Frances B. 
Published: May 2005

AbstractHydrogen T1 values are reported for deoxygenated solutions in CDCl3 of toluene, p‐xylene and nine derivatives in which the CH3 is flanked by one or two chlorine or bromine substituents. Only small differences were observed, the T1 values all being in the range 5.8–12.8 s, and there was no obvious correlation of T1 with structure.
1H and 13C NMR structural assignments of two isomeric isopropylidenepyridoxines
Authors: Nelson Janis T. , Nelson Peter H. 
Published: May 2005

AbstractAcid‐catalyzed reaction between pyridoxine and acetone produced the isomeric six‐ and seven‐membered ketals, depending on the conditions used. The structures were assigned by means of the 1H and 13C NMR spectra of the free bases and hydrochlorides.
Long‐range 1H coupling interactions: Identification of different pathways by 2D NMR δ—δ correlated spectroscopy. Applications in structural analysis
Authors: Platzer N. , Goasdoue N. , Davoust D. 
Published: May 2005

AbstractThe simplest methods of 2D δ‐δ correlated spectroscopy (COSY and COSY LR) allow the easy observation of long‐range coupling interactions. It is shown how these methods can lead to the discrimination between different pathways across single bonds: 4J through coplanar or gauche arrangement of the bonds and 5J through a zig‐zag pathway or bond proximity. Applications to configurational and conformational analysis of polycyclic compounds, a trimer of isophorone, two natural terpenoids (carotol and daucol) and four steroids, are presented.
13C and 31P NMR studies of some aminophosphonium chlorides
Authors: Krannich Larry K. , Kanjolia Ravindra K. , Watkins Charles L. 
Published: May 2005

AbstractThe multinuclear NMR spectral data for an homologous series of tertiary phosphines, R3‐nP(NMe2)n, aminophos‐phonium ions, [R3PNR′R″]+, and phosphonium ions, [R4‐nPMe]+, where R = Me, Et, n‐Pr and Ph, R′ and/or R″ = H, Me and n = 0 and 1 are reported and discussed. Quaternization by alkylation or chloramination causes an increase in the 31P chemical shift (Δ δP is positive), a decrease in the 13C chemical shift (Δ δC is negative) for all carbons, an increase in the magnitudes of 1J(PC), 3J(PC), 3J(PNCH) and 2J(PCH) and a decrease in the magnitude of 2J(PC). Substitution of a Me2N group for an alkyl or aryl group produces an increase in the 31P chemical shift and in the magnitude of 1J(PC). α‐ and β‐deshielding and γ‐shielding effects are noted in the 13C NMR spectra and β‐deshielding and γ‐shielding effects are noted in the 31P NMR spectra with substitution on the phosphorus and nitrogen atoms.
Concerted use of two‐dimensional NMR spectroscopy in the complete assignment of the 13C and 1H NMR spectra of globularin
Authors: Faure R. , Babadjamian A. , Balansard G. , Elias R. , Maillard C. 
Published: May 2005

AbstractThe complete assignment of the proton and carbon spectra of globularin is presented. 13C multiplicities were determined by the DEPT method; the interpretation of the spectra was achieved by comparison of heteronuclear 13C‐1H chemical shift correlation, 1H homonuclear correlation and 1H homonuclear J‐resolved two‐dimensional NMR spectra.
Identification of constituent sugar residues in oligosaccharides by two‐dimensional 1H NMR phase‐sensitive correlated spectroscopy
Authors: Dabrowski Janusz , Ejchart Andrzej , Kordowicz Maria , Hanfland Peter 
Published: May 2005

AbstractPure absorption phase‐sensitive shift‐correlated 1H NMR spectra were shown to furnish complete information on chemical shifts, their connectivities (including one‐ and two‐step remote connectivities) and coupling constants for oligosaccharides of considerable complexity. Therefore, a strategy using these spectra as a first step in ab initio structure elucidation of carbohydrates may require less effort and spectrometer time than alternative strategies exploiting J‐resolved, double quantum and relayed coherence transfer spectra. All these methods and also triple quantum filtered spectra were applied in order to compare their merits and to identify the constituent sugar residues of three peracetylated glycosphingolipids, viz. Galα(1–3)Galβ(1–4)GlcNAcβ(1–3)Galβ(1–4)Glcβ(1–1)Cer(Cer=ceramide),Galα(1–3)Galβ(1–4)GlcNAcβ(1–3)[Galα(1–3)Galβ(1–4)GlcNAcβ(1–6)]Galβ(1–4)GlcNAcβ(1–3)Galβ(1–4)Glcβ(1–1)Cer and GalNAcβ(1–3)Galα(1–4)Galβ(1–4)Glcβ(1–1)Cer(globoside).
Oxygen‐17 quadrupole coupling in liquid acetone
Authors: Ruessink B. H. , Maclean C. 
Published: May 2005

Abstract17O NMR spectroscopy of liquid acetone, oriented in a strong applied electric field, was used to measure one of the principal components of the 17O quadrupole coupling tensor (qct). The component along the carbonyl bond was found to be (±)3.0±0.2 MHz. By comparison with other data in the literature concerning acetone and related molecules, it can be concluded that this value refers to the smallest of the principal components. The proposed NMR method is a powerful technique for obtaining information about qcts in normal liquids.
13C NMR spectra of new condensed tricyclic and tetracyclic pyrazole ring systems
Authors: Světlík Jan , Goljer Igor 
Published: May 2005

AbstractThe 13C NMR spectra of 1‐phenylpyrazolo[4,3‐e]pyrrolo[1,2‐a]pyrazine, its 5‐aza analogue and heterocycles with additional azolo ring annelations are reported.
13C NMR chemical shift assignments for some 2‐substituted cyclic 1,3‐diketones
Authors: Sammes Michael P. , Maini Prem Nath 
Published: May 2005

AbstractComplete 13C NMR chemical shift assignments are reported for 32 cyclic and one acyclic 1,3‐diketones, either unsubstituted or having one or two substituents at the 2‐position. The first two classes exist exclusively in the enol form in (CD3)2SO and as mixed tautomers in CDCl3.
NMR investigation of lipophilic cage ligands 2—Structural assignments and conformational properties of the ligand 12‐hexadecyl ‐7,17,22,27‐tetraoxa‐1,4,10,14‐tetraazatricyclo[12.5.5.54,10] ‐nonacosane and of its sodium, potassium and silver complexes
Authors: Anelli Pier Lucio , Beringhelli Tiziana , Molinari Henriette , Quici Silvio 
Published: May 2005

AbstractTwo‐dimensional homonuclear (COSY, phase‐sensitive double quantum filtered COSY) and heteronuclear shift correlated experiments were employed to characterize fully the cylindrical cage ligand 12‐hexadecyl‐7,17,22,27‐tetraoxa‐1,4,10,14‐tetraazatricyclo[12.5.5.54,10] nonacosane (1) and its sodium, potassium and silver complexes. 13C NMR variable temperature experiments indicated that the free ligand 1 is a mobile molecule in a fast conformational equilibrium at room temperature, whereas its sodium complex is more rigid, some degrees of freedom being allowed in that part of the molecule featuring the longest bridge. The potassium derivative behaves similarly to its sodium counterpart. For the silver complex the differences observed have been attributed to a stronger interaction of the metal ion with nitrogen atoms.
Carbon‐13 chemical shifts assignment of (E)‐styryluracits. (E)‐styrylthiouracils and (E)‐3‐oxothiazolo[3,2‐a]‐6‐styryl‐pyrimidin‐5‐ones
Authors: Łapucha Andrzej , Wyrzykiewicz Elzbieta 
Published: May 2005

AbstractThe 13C NMR spectra of nine isomeric (E)‐styryluracils and (E)‐styrylthiouracils and those of five (E)‐3‐oxothiazolo[3,2‐a]‐6‐styrylpyrimidin‐5‐ones have been fully assigned. The Ai and AiK empirical parameters of p‐ and m‐hydroxystyryl, p‐N,N‐diethylaminostyryl, 5‐ and 6‐vinyl02,4‐diketopyrimidyl, 5‐ and 6‐vinyl‐2‐thio‐4‐ketopyrimidyl and 3‐oxothiazolo[3,2‐a]‐6‐vinyl‐5‐ketopyrimidyl groups were calculated for the prediction of the chemical shifts of substituted (E)‐styryluracils and (E)‐3‐oxothiazolo[3,2‐a]styrylpyrimidin‐5‐ones.
Carbon‐carbon [nJ(CO, C)] and carbon‐fluorine coupling constants [nJ(CF)] of ortho‐substituted benzoic acids and acid fluorides: INDO‐SOS calculations and evaluation of rotational effects
Authors: Hansen Poul Erik , Berg Arne , Schaumburg Kjeld 
Published: May 2005

AbstractCarbon‐carbon coupling constants, nJ(CO, C) were determined for o‐alkylbenzoic acids and benzoyl fluorides and carbon‐fluorine coupling constants, nJ(CF), were determined for the fluorides. INDO‐SOS calculations showed promise for estimating factors that influence the coupling constants, and experimental and theoretical arguments were used in the evaluation of these factors. The coupling constants were investigated for use as parameters in determing the orientation of the acid fluoride group. Through‐space contributions to carbon‐carbon couplings were considered. 13C chemical shifts are briefly discussed in relation to the anisotropy and conformation of the carboxyl and alkyl groups.
13C and 1H NMR chemical shifts of 9‐alkyltriptycenes. Linear variations of 13C chemical shifts on successive substitution of the 9‐methyl hydrogen atoms by methyl groups
Authors: Imashiro Fumio , Hirayama Kei , Saika A. 
Published: May 2005

Abstract13C and 1H NMR chemical shifts of 9‐methyltriptycene (2), 9‐ethyltriptycene (3), 9‐isopropyltriptycene (4) and 9‐tert‐butyltriptycene (5) were measured. The 13C chemical shifts of the carbon atoms at each corresponding position in 2‐5 are proportional to the number of β‐methyl carbon atoms attached to the 9‐methyl (C‐α) carbon atom. Relatively small changes in the 13C chemical shifts of C‐2, C‐3 and C‐4 carbon atoms and nearly constant values for the 1H chemical shifts of the H‐2, H‐3 and H‐4 protons in 2‐5 suggest that the structures of the benzene rings in the 9‐alkyltriptycenes remain almost unaltered, resulting in linear variations of the 13C chemical shifts of the 9‐alkyltriptycenes.
13C NMR of acyloxyalkoxycarbenium salts. Cations formed in reactions of lewis acids with acid chlorides obtained from half‐esters of dicarboxylic acids
Authors: Eyley Stephen C. , Heaney Harry , Sodhi Khushbir S. 
Published: May 2005

Abstract3‐Methoxycarbonylpropanoyl chloride and 4‐methoxybutanoyl chloride interact with Lewis acids to form either donor‐acceptor complexes or delocalized carbenium ions which can be characterized by 13C NMR spectroscopy. The chemical shift values are compared with shifts in model systems obtained by the protonation of glutaric anhydride, γ‐butyrolactone and δ‐valerolactone, and by the methylation of γ‐butyrolactone and δ‐valerolactone.
Proton and carbon‐13 NMR relaxation studies of 2,2‐dichloropropane and 2,2‐dibromopropane
Authors: Aksnes D. W. , Ramstad K. 
Published: May 2005

AbstractProton and 13C line widths and spin‐lattice relaxation times, T1, have been measured for liquid and solid 2,2‐dichloropropane (1) and 2,2‐dibromopropane (2). Molecular self‐diffusion, with activation energies in the range 18‐24 kJ mol−1, is responsible for the considerable line narrowing observed for the NMR spectra in solid I of these substances. The NMR data reveal a previously unreported phase transition point at 208 K for 2.An analysis of the proton and 13C T1 times in both the liquid and solid phases is reported. Effective correlation times, activation energies and pre‐exponential factors for the appropriate motions have been obtained from the Arrhenius equation. The proton and 13C spin‐lattice relaxation mechanisms in the liquid and solid I phases are governed by overall molecular reorientations, with activation energies in the range 9–11 kJ mol−1. The rotational correlation time increases slightly at the liquid → solid I boundary from 3.2 to 3.6 ps for 1 and from 5.1 to 5.4 ps for 2. The correlation time is observed to decrease by five orders of magnitude at the solid I → solid II transition point of 2. The dominant motion causing spin‐lattice relaxation in phase II is methyl group reorientation with an activation energy of 18 kJ mol−1.
Indirect 1H19F1H and 1H19F13C nuclear overhauser enhancements: Anomalous intensity effects and applications in conformational analysis
Authors: Sánchez‐Ferrando Francisco , Sanders Jeremy K. M. 
Published: May 2005

AbstractIndirect nuclear Overhauser enhancements through 19F have been determined for the three‐spin systems 1H‐19F‐1H and 1H‐19F‐13C by steady‐state presaturation of the appropriate proton, and applied to the conformational analysis of 5‐bromo‐2‐fluoro‐4‐nitroacetanilide. The 1H NOE difference spectra at 400 MHz showed antiphase doublets for protons undergoing simultaneous dipolar relaxation with, and scalar coupling to, 19F. Similarly, in the 13C selective NOE difference spectrum at 100 MHz, the two lines of the fluorine‐bearing carbon showed negative enhancement factors of different magnitude on presaturation of the appropriate proton. The use of these anomalous intensity effects in conformational analysis is illustrated.
13C chemical shifts of 1‐cyano‐para‐substituted 1,2‐diphenylcyclopropanes
Authors: Schanck AndréA , Deblock Isabelle , Van Meerssche Maurice , Leroy Georges , Weiler Josy 
Published: May 2005

AbstractFifteen 1 ‐cyano‐l,2‐diphenyl cyclopropane derivatives were analysed by 13C NMR spectroscopy. The chemical shifts for each carbon have been assigned.
Studies of intramolecular electronic effects in chloroacetophenones C6H5COCH3‐n Cln and p‐ClC6H4COCH3‐n Cln by 35Cl NQR
Authors: Nogaj Boleslaw , Schroeder Grzegorz 
Published: May 2005

Abstract35Cl NQR (77 K) spectra for two groups of compounds, C6H5COCH3‐n Cln and p‐ClC6H4COCH3‐nCln, are reported. The frequencies were assigned to individual chlorine atoms in the molecules. Polar effects and mechanisms of conjugation in the molecules are discussed. The influence of the polar carbonyl group on the electronic structure of the molecule and the NQR frequency was studied in detail.
1D‐ and 2D‐NMR study of a nonapeptide, a fragment of collagen, in its free state and complexed with aluminium (III)
Authors: Gervais M. , Commenges G. , Laussac J.‐P. 
Published: May 2005

Abstract1H NMR studies at 250 MHz and 13C NMR studies at 62.8 MHz on the synthetic nonapeptide fragment of type III collagen, Gly‐Lys‐Hyp‐Gly‐Glu‐Hyp‐Gly‐Pro‐Lys (CP9), have been carried out in aqueous solution and DMSO‐d6. The resonances are assigned with the help of 2D correlated spectroscopy, pH titrations by following the characteristic pK values exhibited by protons adjacent to ionization sites and one‐dimensional (1D) spin decoupling techniques. Chemical shifts of the proline and hydroxylproline carbon atoms indicate that the trans configuration about the three X—Pro and XHyp peptide bonds is strongly favoured in all cases, although the minor cis resonances accounting for about 10% of the Pro and Hyp intensity can also be observed. In addition, there appears to be no significant pH sensitivity of the cis ⇌ trans equilibrium. Addition of aluminium causes changes in the spectra, indicating specific interactions with carboxylates of the glutamyl and lysyl residues, as well as a change for both hydroxylproline residues. These data are interpreted by the formation of a 1:2 stoichiometric complex (AlIII‐CP9). the implication of these results with respect to the effect of aluminium in the tanning process is discussed.
Structural studies in the cedrane series by 13C NMR
Authors: Brun P. , Casanova J. , Raju Muppala S. , Waegell B. , Wenkert Ernest , Zahra J. P. 
Published: May 2005

AbstractThe complete analysis of the 13C NMR spectra of 30 cedrane derivatives with various functionalities on the 2, 6, 6, 8‐tetramethyltricyclo[5.3.11,701,5]undecane skeleton is reported. The assignment of the signals to the appropriate carbons has been made using the various functionalities on the molecular framework and the chemical shift theory (α, β, γ effects). When necessary, off‐resonance decoupling, INEPT and DEPT experiments have been used, as well as specific deuterium labelling. The last ambiguities were resolved with the aid of lanthanide shift reagents and SFORD experiments. The assignments for the reference compounds neoisocedranol oxide, cedrol and cedrene were made using the carbon‐carbon connectivity 2D INADEQUATE pulse sequence. The examination of cedrane derivatives functionalized on C‐9 (carbonyl, hydroxyl, acetate) and C‐8 (methyl, axial or equatorial) showed that the 13C chemical shifts of C‐5, ‐6, ‐11 and ‐13 are sensitive probes for the conformation of the six‐membered ring (ring C), which is essentially a flattened chair, and for the stereochemistry of the C‐8 and C‐9 substituents. Comparison with 2‐methylbicyclo[3.2.1]octan‐3‐ones shows that the Anti Reflex effect is operative in cedrane derivatives.Cedrane oxides and their derivatives have also been examined and the corresponding 13C data are reported. Using all this information it was possible to carry out a complete analysis of lac acids, which have a functionalized tricyclo[5.31,7, 01,5]undecane framework like the cedrane derivatives. The 13C spectral analysis shows that, from the structural point of view, this tricyclic system behaves as a bicyclo[3.3.0] skeleton with an additional three‐carbon bridge between C‐1 and C‐7, rather than as a bicyclo[3.2.1]octane with an additional cyclopentane fused on C‐1 and C‐5; when additional strain is introduced into this system, the five‐membered ring A and the six‐membered ring C undergo conformational deformations more easily than ring B.