bluuebunny/crossref_metadata_2025_split huggingface dataset:
Catalytic gas‐phase oxidation of olefins mediated by Fe(C6H6)+ and a comparison of Fe(L)+ complexes (L = benzene, pyridine, naphthalene)
Authors: Stöckigt Detlef , Schwarz Helmut 
Published: July 2007

AbstractThe catalytic potential of Fe(L)+ complexes (L = benzene, pyridine, naphthalene) with respect to oxygen transfer to alkenes in the gas phase has been investigated by using Fourier‐transform ion cyclotron resonance mass spectrometry. Oxidation of Fe(L)+ by N2O leads to Fe(L)O+ with reaction efficiencies of 86% (L = benzene), 40% (L = pyridine), and 44% (L = naphthalene), respectively. While „naked”︁ FeO+ behaves as a powerful CC‐ and CH‐bond activation reagent, the ligated species Fe(L)O+ are entirely unreactive in that respect. However, oxygen transfer from Fe(L)O+ to olefins occurs at the collision rate with less than 10% formation of byproducts. Indirect evidence is presented suggesting that the O‐atom transfer from Fe(L)O+ to olefins does not generate ketones or aldehydes; rather, epoxide formation is brought about. The largest turnover number (nt) is obtained for the Fe(C6H6)O+/C2H 4 system with nt = 6.
Influence of substituents on the rotational energy barrier of atropisomeric biphenyls — studies by polarimetry and dynamic gas chromatography
Authors: Wolf Christian , König Wilfried A. , Roussel Christian 
Published: July 2007

AbstractWe have synthesized a series of 2,2′‐substituted biphenyls and particularly derivatives of 2,2′‐bis(trifluoromethyl)biphenyl (4) with either one or two fluoro, chloro, bromo, amino, nitro or methoxy substituents in the para positions for investigating the influence of these substituents on the rotational energy barrier of the biphenyls by polarimetry and dynamic gas chromatography (DGC). Axially chiral biphenyls with at least two bulky substituents in the ortho positions were separated by gas chromatography on selectively modified cyclodextrins. Due to competition between resolution and enantiomerization in the gas chromatographic column 2‐tert‐butyl‐2′‐isopropyl‐ (2), 2‐isopropyl‐2′‐(trifluoromethyl)biphenyl (5), and some para‐substituted derivatives of 4 show temperature‐dependent interconversion profiles and coalescence phenomena in analogy to dynamic NMR studies. The accelerating effect on the rate of enantiomerization of electron‐donating groups in the para positions and the decelerating effect of electron‐accepting groups has been determined. Dynamic gas chromatography is shown to be a useful supplement to studies of thermal enantiomerization kinetics of optically enriched or separated compounds by polarimetry for the investigation of energy barriers of atropisomeric biphenyls.
Molecular modeling of saccharides, 6. Small‐ring cyclodextrins: Their geometries and hydrophobic topographies
Authors: Immel Stefan , Brickmann Jürgen , Lichtenthaler Frieder W. 
Published: July 2007

AbstractA detailed force‐field‐based evaluation of the molecular geometries of small‐ring cyclodextrins 1–3 with three, four, and five α(1→4)‐linked glucose residues and the starch‐derived α‐cyclodextrin (4) was performed by using molecular mechanics and high‐temperature annealing. The resulting minimum‐energy structures reveal that the progressive strain imposed by diminution of the cyclodextrin macrocycle from six glucose units (α‐CD, 4) to five (cycloglucopentaoside 3), four (tetraoside 2), and three (cyclotrioside 1) is reflected in a widening of the intersaccharidic bond angle, in a complex balance of the interrelated glucose tilt angles τ and the glycosidic torsions Φ and Ψ against each other, and most strikingly, in a specific unilateral distortion of the pyranoid rings, i.e. flattening at C‐4 towards the E1 envelope conformation. This successive levelling at C‐4, induced by a decrease of the two related ring torsion angles, is small in the pentamer 3, pronounced in 2, and fully realized in the cyclotrioside 1. – The respective contact surfaces of the minimum‐energy conformers and their molecular lipophilicity patterns (MLP), in color‐coded form, were also generated, allowing an assessment of their capabilities to form inclusion complexes. Accordingly, only the cyclopentaoside 3 exhibits a hydrophobic central cavity similar to that of α‐CD (4), the smaller cyclodextrins 2 and 1 are closed, yet contain a hydrophobic indentation for potential binding.
New sesquiterpene ethers and other constituents isolated from Brazilian vassoura oil
Authors: Weyerstahl Peter , Christiansen Christian , Marschall Helga 
Published: July 2007

AbstractThree new sesquiterpene ethers, 1,6‐epoxyeudesm‐4(15)‐ene (7), 1,11‐epoxycadina‐4,9‐diene (9) and 5,11‐epoxycadin‐1(10)‐ene (10), some sesquiterpene alcohols, e.g. cis‐ and trans‐dracunculifoliol (3) and 4‐epi‐maaliol (12), as well as 2,2‐dimethyl‐6‐vinylchromene (14) were isolated from Brazilian Vassoura oil. The structures were elucidated by spectroscopic methods.
Radikal‐Stabilisierungsenergie – das MMEVBH‐Kraftfeld
Authors: Roth Wolfgang R. , Staemmler Volker , Neumann Martin , Schmuck Carsten 
Published: July 2007

Radical‐Stabilization‐Energy – the MMEVBH Force FieldMaking use of the VB method of Malrieu et al.[6–10] a force field has been developped, which allows to calculate heats of formation of hydrocarbons (conjugated and non‐conjugated olefins, radicals, and diradicals) with high accuracy. With this method radical stabilization energies (RSE) for a great number of delocalized radicals are calculated and compared with experimental values, derived from shock‐tube measurements of dissociation energies or from rotational barriers of substituted olefins. A detailed analysis of the RSE with respect to structure, substituents, strain, and aromaticity is presented.
Synthesis of vinca alkaloids and related compounds, 73. Synthesis and ring transformations of deethylaspidospermane derivatives. Synthesis of (±)‐20‐deethyl‐3‐oxotabersonine
Authors: Kalaus György , Juhász Imre , Greiner István , Kajtár‐Peredy Mária , Brlik János , Szabó Lajos , Szántay Csaba 
Published: July 2007

AbstractThe reaction of the key compound 14 with methyl 4‐formyl‐butanoate (9) or with 5‐benzoyloxypentanal (13) gave the D‐seco‐aspidospermane derivatives 17 and 18, respectively. Compound 17 was indirectly and 18 was directly converted to (±)‐20‐deethylvincadifformine (7) and (±)‐20‐deethyl‐20‐epivincadifformine (8). Epimerization occurred in both cases. The thioxo compound 23 was used for the synthesis of (±)‐20‐deethyltabersonine (28) and (±)‐20‐deethyl‐3‐oxotabersonine (27). Oxidative ring transformation of the (±)‐20‐deethylvincadifformine (7) gave (±)‐16‐deethylapovincamine (29).
Electrophilic additions to tetradehydrodianthracene
Authors: Herges Rainer , Neumann Helfried 
Published: July 2007

Abstract5,12:6,11‐Di[1,2]benzenodibenzo[a,e]cyclooctene (tetrade‐hydrodianthracene, TDDA) (1) reacts with halogens to give transannular (anti) 4, 5 and ring‐opened (syn) products 6, 7. The product ratio shows a remarkable solvent dependence. Solvents of medium polarity favor anti addition, whereas syn addition is observed both with increasing and decreasing polarity. For instance, chlorine in toluene adds 100% syn, in dichloroethane 56 % anti, and in trifluorethanol again 100% syn. It is concluded that, depending on solvent polarity, three different mechanisms for electrophilic addition are operative.
A new synthesis of (±)‐phoracantholide, (±)‐dihydrorecifeiolide, and (±)‐muscone via α‐nitro ketones
Authors: Ballini Roberto , Marcantoni Enrico , Petrini Marino 
Published: July 2007

AbstractCα′ alkylation of α‐nitro cycloalkanones 1a–c with methyl iodide at −35 to −70°C in THF/heptane/DMPU/TMDA in the presence of LDA as a base furnished the methylated α‐nitro ketones 2a–c. Denitration of 2a, b with Bu3SnH/AIBN in dry benzene afforded the α′‐methylated ketones 3a, b, which were converted to (±)‐phoracantholide (4a) and (±)‐dihydrorecifeiolide (4b), respectively, by the Baeyer‐Villiger oxidation. Reduction of 2c with NaBH4 and dehydration of the obtained nitro alkanol 5 with Al2O3/DMAP furnished the corresponding nitro alkene 6. Nef conversion of 6 with sodium hypophosphite and Raney nickel afforded (±)‐muscone (7) in good yields.
Benzodiimidazoles by reaction of benzenetetramines and benzenehexamines with dimethylformamide and its dimethyl acetal
Authors: Mataka Shuntaro , Shimojyo Yoshiro , Hashimoto Iwao , Tashiro Masashi 
Published: July 2007

AbstractBenzo[1,2‐d;3,4‐d′]‐ (9) and ‐[1,2‐d;‐4,5‐d′]diimidazole (10) were prepared by reactions of the corresponding benzenetetramines 1 and 2 with N,N‐dimethylformamide or N,N‐dimethylformamide dimethyl acetal 4. The corresponding reaction of benzenehexamine (3) gave the benzo[1,2‐d;4,5‐d′]diimidazole derivative 8.
Photochemistry of Phenyl Azides Bearing 2‐Hydroxy and 2‐Amino Groups Studied by Matrix‐Isolation Spectroscopy: Generation and Characterization of Reactive o‐Quinoid Compounds
Authors: Tomioka Hideo , Matsushita Takeshi , Murata Shigeru , Koseki Shiro 
Published: July 2007

AbstractBroad‐band irradiation (λ > 370 nm) of 2‐hydroxyphenyl azide (1) in Ar at 10K monitored by IR resulted in the formation of at least three major products, all of which were shown to be photointerconvertible under these conditions. The two products showing carbonyl stretching absorption bands were assigned to an E/Z mixture of 6‐imino‐2,4‐cyclohexadien‐1‐one (3), while the product showing sharp absorption bands in the cumulenic double bond region was assigned to 6‐imino‐1,3,5‐hexatrien‐1‐one (4). These assignments were fully supported by comparison of the experimental IR spectra with the theoretical data calculated at the HF/6‐31G** level of theory. Similar irradiation (λ > 350 nm) of 2‐aminophenyl azide (6) in Ar at 10 K also afforded three photointerconvertible products, which were assigned to a mixture of (E,E)‐(E,Z)‐ and (Z,Z)‐1,2‐diimino‐3,5‐cyclohexadiene (8). The assignments were again supported by ab initio calculations. The reactions are discussed in terms of a 1,4 H shift in the photolytically generated phenylnitrenes (2 and 8) from the azides (1 and 7).
Comparison of the One‐Bond Nucleophilicities of Monomethyl‐ and Dimethyl‐Substituted 1,3‐Butadienes
Authors: Mayr Herbert , Hartnagel Manfred 
Published: July 2007

AbstractThe kinetics of the reactions of (E)‐2‐methyl‐1,3‐pentadiene (2a), 4‐methyl‐1,3‐pentadiene (2b), and (Z)‐1,3‐pentadiene (2c) with benzhydryl cations have been studied photometrically in dichloromethane solution. Substitution of these rate constants into the linear free enthalpy relationship lgk=s(N + E) yielded the nucleophilicity parameters N for these dienes. The influence of methyl groups on the nucleophilic reactivities of 1,3‐butadienes is discussed, and a system to estimate reactivities of further alkylated 1,3‐dienes is suggested.
Matrix Isolation of o‐Quinoid Compounds – 6‐Imino‐2,4‐cyclohexadien‐1‐one and 1,2‐Diimino‐3,5‐cyclohexadiene
Authors: Morawietz Jens , Sander Wolfram 
Published: July 2007

Abstract6‐Imino‐2,4‐cyclohexadien‐1‐one (1b) and 1,2‐diimino‐3,5‐cyclohexadiene (1c) were generated in high yields from o‐azidophenol (5b) and o‐azidoaniline (5c), respectively, by irradiation in argon matrices at 10 K or by flash vacuum pyrolysis (FVP) with subsequent trapping of the products in solid argon. The hydrogen shift in the phenylnitrenes 6 formed as primary intermediates is very rapid, and thus the nitrenes are short‐lived transients even under the conditions of matrix isolation. Ring expansion to azacycloheptatetraenes was not observed. FVP produces the thermodynamically most stable E/Z isomers of the quinones as the main products. Photolysis of the matrix‐isolated quinones results in photostationary equilibria of the E/Z isomers. The stereoisomers were identified by comparison of the matrix IR spectra with ab initio calculations at the RMP2‐FC‐6/31G(d) level of theory.
The Configuration of (+)‐8‐Ethylnorlobelol‐I; a Correction of the Literature
Authors: Mill Sibel , Durant Alex , Hootelé Claude 
Published: July 2007

AbstractThe piperidine alkaloid (+)‐8‐ethylnorlobelo‐I is assigned the revised 2S,8,S absolute configuration as depicted in 7. LiAl(O‐tBu)3H reduction of the ketone rac‐5 proceeded with a high stereoselectivity to give, after hydrolysis of the carbamate function, the syn amino alcohol rac‐6. Inversion of the C‐8 configuration of ent‐6 yielded (‐)‐8‐ethylnorlobelol‐I ent‐7. A short nitrone‐alkene‐based synthesis of rac‐7 has been developed.
Relative and Absolute Configuration of the 3,12‐Dihydroxypalmitic Acids
Authors: Jakob Barbara , Gerlach Hans 
Published: July 2007

AbstractThe relative and absolute configuration of (+)‐3,12‐dihydroxypalmitic acid, a constituent of the Ipomea operculata M. resin, has been determined by synthesis. Dimethyl L‐malate was converted via (S)‐(+)‐1 into the oxirane (S)‐(‐)‐2. Reaction of (‐)‐2 with the Grignard reagent of 8‐benzyloxybromooctane provided (S)‐(+)‐3 in 84% yield, and this was converted into the aldehyde (S)‐(‐)‐6 via (S)‐(‐)‐4 and (S)‐(‐)‐5. Reaction with the lithium enolate of methyl acetate gave 7 and 8, which could be converted via 9 and 10, 11 and 12, 13 and 14 into the lactones (4S,13S)‐(+)‐15 and (4R,13S)‐(+)‐16 and finally into the methyl esters (3S,12S)‐(+)‐17 and (3R,12S)‐(+)‐18 and acids (‐)‐19 and (+)‐20. The erythro configuration of (+)‐17 was established by a stereoselective synthesis starting from (S)‐(‐)‐2 via (S)‐(+)‐21, (+)‐22, (+)‐23, the Grignard reagent of (+)‐24 and (R)‐(+)‐2‐(2‐benzyloxyethyl)oxirane to give (3S,12S)‐(‐)‐25, (‐)‐26, (+)‐27 and (+)‐28, which could be oxidized to the diacetoxy acid (3S,12S)‐(+)‐29. Saponification and esterification gave (3S,12S)‐(‐)‐19 and (3S,12S)‐(+)‐17, with properties identical to those of (+)‐17 obtained from the resin glycoside.
Synthesis of (−)‐Streptenol A, (±)‐Streptenol B, C and D
Authors: Blechert Siegfried , Dollt Heribert 
Published: July 2007

Abstract2‐(2,2‐Dimethyl‐1,3‐dioxan‐4‐yl)acetaldehyde (3) was used for the preparation of streptenol A and B (Scheme 1) via a Grignard reaction with 1‐bromopent‐3‐ene. Hereby optically pure (4′R)‐3 gave the antipode of Streptenol A. Reaction with lithiated 1‐pentyne opened access to streptenol C and D. To obtain the dienone structure of streptenol C and D, a palladium‐catalyzed alkynone isomerization was induced. Kinetic differences in the acid‐mediated cleavage of the 1,3‐acetonide protected 1,3,5‐triol system caused the stereoselectivity in the natural products. So only the (3S*,5R*) acetonide of streptenol B reacted under mild hydrolytic conditions and gave after transacetalization first a 3,5‐protected streptenol B with pure relative stereochemistry and finally (3S*,5R*)‐streptenol B.
Chemistry of Opium Alkaloids, XLIII – A PM3 Computational Approach to the Selectivity in the Diels‐Alder Reactions of Thebaine and Analogues with Methyl Propenoate
Authors: Baas Jan M. A. , Woudenberg Richard H. , Maat Leendert 
Published: July 2007

AbstractGeometrically fully‐optimized transition structures are calculated for the Diels‐Alder adducts of methyl propenoate and the 3‐demethoxy derivatives of the dienes thebaine, 6‐demethoxythebaine, 5β‐methylthebaine, and 5β‐methyl‐6‐demethoxythebaine using the semiempirical PM3 method. The number of calculated forms is limited according to a search of the conformational space of methyl propenoate and of the dienes. The lengths of the incipient bonds in the transition structures vary from 2.0 to 2.4 Å, but the average value of the lengths of these two bonds in the same structure is much more constant: 2.18 ± 0.02 Å. The effects of the methoxycarbonyl group and of the 6‐methoxy group on the lengths of the incipient bonds are in agreement with the relative magnitudes of the frontier orbital coefficients. Comparison of the energetic data with experimental results shows that the prediction of the stereo‐ and regioselectivities from the Gibbs energy of activation differences is good as far as it concerns the main products. The absence of minor products and the formation of the remarkably large amount of 8β‐ethoxycarbonyl‐6β,14β‐ethenomorphinan from 5β‐methyl‐6‐demethoxythebaine does not follow from the calculations.
Reactions of 3,5‐Diaryl‐1,2‐dithiolium Salts and 3,5‐Diaryl‐1,2,4‐dithiazolium Salts with Metal Cyclopentadienides
Authors: Hartke Klaus , Kraska Andreas , Massa Werner , Molinier Michel , Wocadlo Sigrid 
Published: July 2007

AbstractReaction of the 3,5‐diaryl‐1,2‐dithiolium salts 2 with the metal cyclopentadienides 4 and 9 leads to the formation of the tricyclic compounds 6 and 10 via a ring‐opened intermediate, which undergoes an intramolecular Diels‐Alder cyclization. Compounds 6 and 10 rearrange by treatment with boron trifluoride‐diethyl ether to the isomeric compounds 7 and 11. The structures 6f and 7f were confirmed by X‐ray analysis. Condensation of the 3,5‐diaryl‐1,2,4‐dithiazolium salts 3 with the metal cyclopentadienides 4 affords the tricyclic compounds 12, which do not rearrange by Lewis acid catalysis.
Stereoselectivity of 7‐Methyl‐7‐norborn(en)yl Cations
Authors: Herrmann Roland , Kirmse Wolfgang 
Published: July 2007

Abstract7‐Methyl‐7‐norbornyl cations were generated, starting from 1‐methylbicyclo[3.2.0]hept‐2‐yl substrates. While the exo diazonium ion (26) reacted exclusively with migration of the C‐1–C‐7 bond, competitive shifts of C‐7 and C‐5 were observed with the endo diazonium ion (25) and the endo brosylate (24). The stereorandom capture of 7‐methyl‐7‐norbornyl cations was demonstrated by means of deuterium labels, thus supporting the classical structure 12 (C2v). The inductive and hyperconjugative effects of the 7‐Me group in 12 override the σ delocalization that is characteristic of the analogous secondary cation (7, C1). 1,2‐Dimethylbicyclo[3.2.0]hept‐2‐yl cations (34), labeled with deuterium, were shown to give 1,7‐dimethyl‐7‐norbornanol (35) without undergoing a degenerate shift of C‐5. A variety of 1‐methylbicyclo[3.2.0]hept‐6‐en‐2‐yl substrates were found to display a similar pattern of rearrangements as their saturated analogs. However, the 7‐methyl‐7‐norbornenyl cation (48) thus generated accepts nucleophiles stereoselectively, i.e., the delocalization of π electrons to C‐7 is not affected by methyl substitution.
Photoactive Phanes, II. – X‐ray Structure and Photoreactivity of pseudo‐gem Cinnamophane Dicarboxylic Acid {bis‐4,15‐(2′‐Hydroxycarbonylvinyl)[2.2]paracyclophane}
Authors: Meyer Ulrich , Lahrahar Nacer , Marsau Pierre , Hopf Henning , Greiving Helmut , Desvergne Jean‐Pierre , Bouas‐Laurent Henri 
Published: July 2007

AbstractThe pseudo‐gem cinnamophane dicarboxylic acid 1 was shown to undergo a stereospecific [2 + 2] photocycloaddition in the solid state, generating the truxinic acid derivative 2 in 100% chemical yield; the reaction can proceed to completion because it is not an “independent site” solid state reaction. The X‐ray structure of 1 reveals that its molecules are associated in dimers formed from four almost linear hydrogen bonds. A salient feature is the intramolecular centre‐to‐centre distance between the reacting double bonds of ≈3.37 Å, the smallest known to date. In contrast to trans‐cinnamic acid, the topochemical [2 + 2] photocycloaddition occurs also in solution, with a quantitative chemical yield and a quantum yield of ≈0.55 (in methanol).
Bimolecular Formation of Radicals by Hydrogen Transfer, 12. – Transfer hydrogenation of p‐Substituted α‐Methylstyrenes and of 9‐Methylenefluorene as a Criterion of Mechanism
Authors: Friebolin Heike , Roers Rolf , Ebenhoch Jochen , Gerst Matthias , Rüchardt Christoph 
Published: July 2007

AbstractThe uncatalyzed transfer hydrogenation of substituted α‐methylstyrenes with 9,10‐dihydroanthracene (DHA), xanthene (XAN), or 9,10‐dihydroacridine (DHAC) was studied mechanistically. The three hydrogen donors react at very similar rates and with similar activation parameters and with little discrimination between the various substituted styrenes. The kinetic isotope effects are also similar and the solvent effect is small. A hydrogen atom transfer mechanism (retrodisproportionation) is, therefore, preferred to a hydride transfer mechanism. This is supported by the very similar reactivity of the hydrogen transfer reaction of DHA and XAN with 9‐methylenefluorene. The product yields in all reactions investigated in this project were >90%.
New Synthetic Routes to Alkyl‐Substituted and Functionalized Perylenes
Authors: Schlichting Peter , Rohr Ulrike , Müllen Klaus 
Published: July 2007

Abstract3,9(10)‐Dialkynyl‐ and 3‐monoalkynyl‐substituted perylenes (16 and 20) and their ω‐functionalized derivatives 27, 30, 33, 35 can be synthesized easily and in high yields as well as the 3‐alkyl‐9(10)‐alkynyl‐substituted perylenes 39 and 42. This is achieved by a palladium‐catalyzed coupling reaction of monobromoperylenes 19 and 38 and dibromoperylene 15 with 1‐alkynes and ω‐functionalized 1‐alkynes, respectively. The quantitative conversion of the alkynes into the corresponding alkyl‐substituted perylene derivatives 17, 21, 28, 31, 34, 36, 40 and 43 can be accomplished by catalytic hydrogenation. Further conversions of 28, 31, 34, 36, 40 and 43 provide the functionalized perylenes 29, 32, 37, 41 and 44.
Rotaxanes with Chiral Stoppers and Complexation of Cations by Podand Axles with Sugar Terminal Groups
Authors: Archut Andreas , Müller Walter Manfred , Baumann Sven , Habel Mathias , Vögtle Fritz 
Published: July 2007

AbstractThe new π‐donor/π‐acceptor type rotaxanes 15, 16 bearing chiral sugar units as blocking groups have been synthesized in 2% and 6% yield, starting from acetobromo glucose 10 and the podands 8 or 9, followed by the reaction of the resulting axles 11 and 12 with the dicationic bis(bipyridinio) wheel precursor 13 and the bis(bromomethyl) compound 14. The capability of the podands 11 and 12 and of the rotaxanes 15 and 16 to form podate‐like complexes with metal salts was investigated by NMR; the effect of metal thiocyanate salt addition was monitored. Distinct changes of proton shifts that indicate complex formation were only observed between the free axles 11, 12 and the metal salts, whereas no major effects were found in case of the rotaxanes 15, 16. Glucose entities were chosen as stopper units in order to support metal complexation as terminal groups and to introduce a source of chirality into the molecules.
Synthesis of Sterically Rigid Macrocycles by The Use of Pressure‐Induced Repetitive Diels–Alder Reactions
Authors: Benkhoff Johannes , Boese Roland , Klärner Frank‐Gerrit 
Published: July 2007

AbstractSyntheses of syn‐dimethanotetrahydroanthracene, ‐tetracene, and ‐pentacene derivatives 8a–d, 9a–d, and syn‐25 are described. Highly stereoselective, pressure‐induced Diels‐Alder reactions of the bis‐dienophiles 8a and/or 9a with the bis‐diene 7 lead to the sterically rigid macrocycles 1a, 2a, and 3a/3b, which have well defined cavities of different sizes.
Differential Recognition of Chirality at C‐2 of 2‐Fluoro‐ and 2‐Methylmevalonate by Mevalonate Kinase – Absolute Configuration of Enzymatically Active 2‐Fluoromevalonate
Authors: Wilde Jürgen , Eggerer Hermann 
Published: July 2007

AbstractBoth 2‐methyl‐ and 2‐fluoromevalonate are alternative substrates of mevalonate kinase, but only the fluorinated compound is phorphorylated stereospecifically with respect to the chiral C‐2. The absolute configuration of the racemic pairs of 2‐fluoromevalonate is deduced from 1H‐ and 13C‐NMR data. The fluorine substituent shifts the equilibrium between the conformers of mevalolactone. Coupling constants found experimentally for 2‐fluoromevalonate are calculated satisfactorily with INDO‐MO data. Enzymatic analysis of components of the racemic pairs of 2‐fluoromevalonate with mevalonate kinase combined with NMR data yield the absolute configuration of the enzymatically active steroisomer, (2R,3R)‐2‐fluoromevalonate.